2 tablespoons vegetable oil, such as safflower
1 small onion, finely chopped
1/2 yellow or orange bell pepper, chopped
1 celery stalk, finely chopped
Coarse salt and ground pepper
1 pound ground dark-meat chicken
4 hamburger buns
Lettuce, tomato, and mayonnaise, for serving
In a large skillet, heat 1 tablespoon oil over medium. Add onion, bell pepper, and celery; season with salt and pepper. Cook, stirring occasionally, until tender, 8 to 10 minutes. Transfer to a medium bowl; cool to room temperature (reserve skillet).
Add chicken to vegetable mixture in bowl; season with 1/2 teaspoon salt and 1/4 teaspoon pepper. Mix to combine. Shape mixture into four 4-inch-wide patties.
In reserved skillet, heat remaining tablespoon oil over medium; cook patties until browned and cooked through, 6 to 8 minutes per side. Place chicken burgers on buns, and top with lettuce, tomato, and mayonnaise.
Recipe shared from: http://www.marthastewart.com/315255/chicken-burgers?czone=food/dinner-tonight-center/dinner-tonight-main-courses¢er=276948&gallery=275660&slide=283139