Season the chicken breasts generously with salt and pepper.
Heat the avocado oil in a large skillet over medium heat.
Cook the chicken for 5–7 minutes per side, or until the internal temperature reaches 165°F. Transfer to a cutting board and let rest for 5 minutes before slicing.
Divide the chopped lettuce among serving bowls.
Top with sliced chicken, corn salsa, pickled red onions, avocado, and black beans, if using.
Drizzle generously with the jalapeño ranch dressing.
Finish with fresh cilantro, crushed tortilla chips or tortilla strips, Cotija cheese, and a squeeze of fresh lime, if desired.