Crispy Onion Chicken Sandwich (Printable)

Buttermilk-marinated fried chicken with crispy onions and garlic aioli on a soft brioche bun.

# What You’ll Need:

→ Chicken & Marinade

01 - 4 boneless, skinless chicken thighs
02 - 1 cup buttermilk
03 - 1 teaspoon garlic powder
04 - 1 teaspoon paprika
05 - ½ teaspoon salt
06 - ½ teaspoon black pepper

→ Breading

07 - 1 cup all-purpose flour
08 - ½ cup cornstarch
09 - 1 teaspoon smoked paprika
10 - 1 teaspoon salt
11 - ½ teaspoon ground black pepper

→ Crispy Onions

12 - 1 large yellow onion, thinly sliced
13 - ½ cup all-purpose flour
14 - ½ teaspoon salt
15 - ½ teaspoon black pepper
16 - Vegetable oil for frying

→ Aioli

17 - ½ cup mayonnaise
18 - 1 large garlic clove, minced
19 - 1 tablespoon lemon juice
20 - ½ teaspoon Dijon mustard
21 - Salt and pepper to taste

→ Assembly

22 - 4 brioche buns, sliced
23 - Butter for toasting buns
24 - Lettuce leaves

# Steps:

01 - In a bowl, whisk together buttermilk, garlic powder, paprika, salt, and black pepper. Add chicken thighs, ensuring complete coverage. Cover and refrigerate for at least 30 minutes or up to 4 hours.
02 - In a shallow dish, combine flour, cornstarch, smoked paprika, salt, and black pepper.
03 - In a separate bowl, toss sliced onions with flour, salt, and black pepper until evenly coated.
04 - Heat 1 inch of vegetable oil in a large skillet to 350°F. Fry onions in batches for 2-3 minutes until golden and crisp. Drain on paper towels.
05 - Remove chicken from marinade, allowing excess buttermilk to drip off. Dredge each thigh in breading mixture, pressing firmly to ensure adherence.
06 - Fry chicken in the same hot oil for 5-7 minutes per side until cooked through and golden brown. Transfer to a wire rack or paper towels to drain.
07 - In a small bowl, combine mayonnaise, minced garlic, lemon juice, Dijon mustard, salt, and pepper.
08 - Butter and toast brioche buns in a skillet until golden brown on all sides.
09 - Spread aioli on both sides of each bun. Layer with lettuce, fried chicken thigh, and a generous portion of crispy onions. Top with bun.

# Expert Advice:

01 -
  • The buttermilk soak keeps the chicken so tender you can practically pull it apart with a fork, even after frying.
  • Crispy onions add a sweet, crunchy contrast that makes every bite feel like a flavor explosion.
  • The garlic aioli ties everything together without overpowering the chicken, just a creamy, tangy hug.
  • Brioche buns toast up buttery and soft, turning this into something that feels restaurant fancy but cooks up in your own kitchen.
02 -
  • Don't skip the buttermilk soak, I tried once with plain milk and the chicken was noticeably drier and less flavorful.
  • Use a thermometer to check your oil temperature, too hot and the crust burns before the chicken cooks through, too cool and it gets greasy.
  • Press the breading onto the chicken firmly, loose coating falls off in the oil and leaves you with bald spots.
  • Let the fried chicken rest on a wire rack instead of paper towels if you can, it keeps the bottom from steaming and losing its crispness.
03 -
  • Double fry the chicken if you want an even crunchier crust, fry once at 325°F until just cooked, let it rest, then fry again at 375°F for a minute to crisp up the outside.
  • Add a tablespoon of pickle juice to the aioli for a tangy kick that cuts through the fried richness beautifully.
  • Use leftover buttermilk marinade to soak chicken for another recipe, but never reuse marinade that touched raw meat without boiling it first.
  • If your oil smokes, it's too hot, pull it off the heat for a minute and let it cool before continuing.
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