Juicy marinated grilled chicken with crispy bacon, creamy avocado, juicy tomato, and crisp lettuce all on top of a brioche bun.
In a bowl, stir together oil, lemon juice, soy sauce, balsamic vinegar, brown sugar, garlic, salt, and pepper. Pierce chicken breasts with a fork all over. Place in a large Ziploc bag. Pour marinade over chicken. Let marinate for at least 30 minutes. 4 - 5 hours is ideal.
Preheat grill to medium heat. Brush grill with oil to prevent sticking.Place chicken on the grill. Cook for approximately 5 - 6 minutes per side, depending on the thickness of chicken. The internal temperature of the chicken should reach 165 degrees. Remove chicken from grill and let rest for 5 minutes.
Cook bacon until crispy. Set aside.
Spread mayonnaise on brioche buns. Spread avocado on one side. Top with chicken, bacon, tomatoes, lettuce, and red onion.