Crispy Onion Chicken Sandwich

Featured in: Everyday Meal Ideas

This mouthwatering sandwich combines buttermilk-marinated fried chicken thighs with golden crispy fried onions and homemade garlic aioli, all stacked on a toasted brioche bun. The chicken marinates for up to 4 hours for maximum tenderness, then gets breaded with a seasoned flour and cornstarch mixture for ultimate crispiness.

Serve immediately while the chicken is still hot and the onions remain crunchy. Optional additions include fresh lettuce, pickles, or coleslaw for extra texture and tang.

Updated on Sun, 18 Jan 2026 11:45:00 GMT
The crispy onion chicken sandwich on a brioche bun is topped with golden fried onions and creamy aioli.  Save
The crispy onion chicken sandwich on a brioche bun is topped with golden fried onions and creamy aioli. | claroamezruy.com

The sizzle hit my ears before the smell did. I was standing over a cast iron skillet, watching onions turn from pale ribbons into crackling golden curls, when I realized this sandwich was going to ruin me for every drive-thru version forever. My sister had just texted asking what I was making for dinner, and I sent her a photo of the chicken marinating in buttermilk. She showed up twenty minutes early.

I made these sandwiches the night my neighbor came over to borrow a ladder and ended up staying for dinner. He stood by the stove, watching me fry the onions in batches, and said it smelled better than the diner his dad used to take him to as a kid. We ate standing up at the counter because neither of us wanted to wait long enough to set the table. He still brings it up every time he sees me.

Ingredients

  • Boneless, skinless chicken thighs: Thighs stay juicier than breasts and handle the heat without drying out, plus they soak up the buttermilk marinade like a sponge.
  • Buttermilk: The acidity tenderizes the meat and adds a subtle tang that balances the richness of the fried coating.
  • Garlic powder and paprika: These bring warmth and depth to both the marinade and the breading without overpowering the chicken.
  • All-purpose flour and cornstarch: The cornstarch is the secret to that extra-crispy, almost crackling crust that holds up even after the sandwich sits for a minute.
  • Smoked paprika: A little smokiness in the breading makes the whole sandwich taste like it came off a grill, even though it is fried in a skillet.
  • Yellow onion: Thinly sliced and fried until golden, these onions add sweetness and crunch that cuts through the richness of the aioli.
  • Mayonnaise: The base of the aioli, it clings to every surface and carries the garlic and lemon into every bite.
  • Garlic clove: Fresh garlic gives the aioli a sharp, clean bite that mellows just enough when mixed with the mayo and lemon.
  • Lemon juice: Brightens everything and keeps the aioli from feeling too heavy.
  • Dijon mustard: Just a touch adds a subtle tang and helps emulsify the aioli so it stays smooth.
  • Brioche buns: Soft, slightly sweet, and sturdy enough to hold all the layers without falling apart in your hands.
  • Vegetable oil: Neutral flavor and a high smoke point make it perfect for frying without any burnt taste.

Instructions

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Marinate the Chicken:
Whisk together buttermilk, garlic powder, paprika, salt, and black pepper in a bowl, then submerge the chicken thighs completely. Cover and let them sit in the fridge for at least 30 minutes, or up to 4 hours if you have the time.
Prepare the Breading:
In a shallow dish, combine flour, cornstarch, smoked paprika, salt, and black pepper, mixing well so the spices are evenly distributed. Set it beside your marinating chicken so you are ready to dredge.
Coat the Onions:
Toss the sliced onions with flour, salt, and black pepper in a separate bowl, making sure each ring is lightly dusted. Shake off any excess before frying.
Fry the Onions:
Heat about 1 inch of vegetable oil in a large skillet to 350°F, then fry the onions in small batches for 2 to 3 minutes until they turn golden and crisp. Drain them on paper towels and try not to eat them all before assembly.
Bread the Chicken:
Remove each thigh from the buttermilk, letting the excess drip off, then press it firmly into the breading mixture on both sides. The coating should stick well and look thick.
Fry the Chicken:
Fry each piece in the same hot oil for 5 to 7 minutes per side, until the crust is deep golden and the internal temperature reaches 165°F. Transfer to a wire rack to let the steam escape and keep the crust crispy.
Mix the Aioli:
In a small bowl, stir together mayonnaise, minced garlic, lemon juice, Dijon mustard, salt, and pepper until smooth. Taste it and adjust the seasoning if needed.
Toast the Buns:
Butter the cut sides of the brioche buns and toast them in a skillet over medium heat until golden and slightly crisp. This step is optional but makes a big difference in texture.
Assemble the Sandwiches:
Spread aioli generously on both sides of each bun, then layer with lettuce if using, a fried chicken thigh, and a big pile of crispy onions. Press the top bun gently and serve immediately.
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Buttermilk-marinated fried chicken is layered with crunchy onions and fresh lettuce inside a soft brioche bun.  Save
Buttermilk-marinated fried chicken is layered with crunchy onions and fresh lettuce inside a soft brioche bun. | claroamezruy.com

The first time I packed one of these sandwiches for lunch the next day, I worried it would get soggy. Instead, I found myself sitting in my car at noon, unwrapping foil, and biting into something that somehow tasted even better cold. The aioli had soaked into the bun just enough, and the onions still had a little snap left. It became my favorite kind of leftover.

How to Store and Reheat

Store the fried chicken and onions separately from the buns and aioli in airtight containers in the fridge for up to 3 days. To reheat, place the chicken on a wire rack over a baking sheet and warm it in a 375°F oven for 10 to 12 minutes until the crust crisps up again. The onions can be reheated the same way for about 5 minutes, though they lose a bit of their crunch no matter what you do. Assemble the sandwiches fresh with new aioli and toasted buns for the best results.

Ways to Customize

If you want heat, stir hot sauce or a pinch of cayenne into the aioli, or add it directly to the breading for a spicy crust. Swap the lettuce for tangy slaw or bread and butter pickles to cut through the richness. You can also use chicken breasts instead of thighs, just watch the cooking time closely so they do not dry out. For a lighter version, bake the breaded chicken at 425°F on a greased rack for about 20 minutes, flipping halfway, though it will not be quite as crispy.

Serving Suggestions

These sandwiches are rich enough to stand on their own, but a handful of crispy fries or a simple green salad on the side balances the plate. I like serving them with cold beer or iced tea, and always a stack of napkins because they get messy in the best way. If you are feeding a crowd, set out extra aioli, pickles, and hot sauce so everyone can build their sandwich exactly how they like it.

  • Serve with sweet potato fries or regular fries for a classic pairing.
  • Add a side of coleslaw or pickles for a tangy contrast.
  • Offer extra aioli and hot sauce on the side so guests can customize their heat level.
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A golden fried chicken sandwich features crispy onions and creamy aioli, served on a toasted brioche bun. Save
A golden fried chicken sandwich features crispy onions and creamy aioli, served on a toasted brioche bun. | claroamezruy.com

Once you make this sandwich at home, it is hard to go back to ordering one out. You will know exactly how good it can be.

Recipe FAQs

How long should the chicken marinate?

Marinate the chicken thighs in buttermilk for at least 30 minutes. For best results and more tender, flavorful chicken, refrigerate up to 4 hours.

Can I use chicken breasts instead of thighs?

Yes, chicken breasts work well as a substitute. They're leaner than thighs but may dry out slightly. Keep cooking time similar or check for doneness around 5-6 minutes per side.

What oil temperature is best for frying?

Maintain the oil at 350°F (175°C) for both the chicken and onions. Use a thermometer to ensure consistent temperature throughout frying for even browning and proper cooking.

How do I keep the sandwich crispy when assembled?

Assemble the sandwich just before serving while the chicken is still warm and onions are crisp. Spread aioli on both bun sides to create a slight moisture barrier that helps maintain texture.

Can I prepare components ahead of time?

Marinate the chicken up to 4 hours ahead. Make the aioli and toast buns 1-2 hours prior. Fry the chicken and onions just before assembly for optimal crispiness and warmth.

What sides pair well with this sandwich?

Serve with pickles, coleslaw, french fries, or fresh salad. The cool, tangy sides complement the rich, crispy sandwich beautifully.

Crispy Onion Chicken Sandwich

Buttermilk-marinated fried chicken topped with crunchy fried onions and creamy aioli on a soft brioche bun.

Prep Time
25 min
Time to Cook
25 min
Total Duration
50 min
Created by Elaine Schwartz


Skill Level Medium

Cuisine American

Portion Size 4 Serves

Diet Preferences None specified

What You Need

Chicken & Marinade

01 4 boneless, skinless chicken thighs
02 1 cup buttermilk
03 1 teaspoon garlic powder
04 1 teaspoon paprika
05 1/2 teaspoon salt
06 1/2 teaspoon black pepper

Breading

01 1 cup all-purpose flour
02 1/2 cup cornstarch
03 1 teaspoon smoked paprika
04 1 teaspoon salt
05 1/2 teaspoon ground black pepper

Crispy Onions

01 1 large yellow onion, thinly sliced
02 1/2 cup all-purpose flour
03 1/2 teaspoon salt
04 1/2 teaspoon black pepper
05 Vegetable oil for frying

Aioli

01 1/2 cup mayonnaise
02 1 large garlic clove, minced
03 1 tablespoon fresh lemon juice
04 1/2 teaspoon Dijon mustard
05 Salt and black pepper to taste

Assembly

01 4 brioche buns, sliced
02 Butter for toasting buns, optional
03 Lettuce leaves, optional

How To Make

Step 01

Prepare Marinade: In a mixing bowl, whisk together buttermilk, garlic powder, paprika, salt, and black pepper. Submerge chicken thighs ensuring full coverage. Cover and refrigerate for 30 minutes minimum, up to 4 hours.

Step 02

Mix Breading Mixture: Combine flour, cornstarch, smoked paprika, salt, and black pepper in a shallow dish. Set aside for dredging.

Step 03

Coat Onions: In a separate bowl, toss sliced onions with flour, salt, and black pepper until evenly coated.

Step 04

Fry Onions: Heat 1 inch of vegetable oil in a large skillet to 350°F. Working in batches, fry onions for 2-3 minutes until golden and crispy. Transfer to paper towels to drain.

Step 05

Bread Chicken: Remove chicken from marinade, allowing excess buttermilk to drip away. Dredge each thigh thoroughly in breading mixture, pressing gently to ensure adhesion.

Step 06

Fry Chicken: Fry breaded chicken in the same oil for 5-7 minutes per side until golden brown and internal temperature reaches 165°F. Drain on a wire rack or paper towels.

Step 07

Prepare Aioli: Whisk together mayonnaise, minced garlic, lemon juice, Dijon mustard, salt, and pepper in a small bowl until smooth and emulsified.

Step 08

Toast Buns: Optional: Butter and toast brioche buns in a skillet over medium heat until golden on both sides.

Step 09

Assemble Sandwich: Spread aioli on both cut sides of each brioche bun. Layer with lettuce if desired, followed by fried chicken thigh, a generous portion of crispy onions, and top half of bun.

Tools Needed

  • Mixing bowls
  • Large skillet or deep fryer
  • Cooking tongs
  • Wire cooling rack or paper towels
  • Chef's knife and cutting board

Allergy Info

Always look over ingredients for allergens. When unsure, ask your healthcare provider.
  • Contains eggs in mayonnaise
  • Contains wheat in flour and brioche buns
  • Contains milk in buttermilk and butter
  • Contains mustard in aioli
  • May contain soy or other allergens in brioche buns

Per Serving Nutrition

These nutrition details are for reference only—talk to your doctor for personal advice.
  • Kcal: 670
  • Fats: 32 g
  • Carbohydrates: 61 g
  • Proteins: 32 g