Rub the chicken with the olive oil and 1.5 tablespoons of the taco seasoning.
Cook the chicken in a hot skillet for 5 to 6 minutes per side until fully cooked. Let rest, then slice.
Whisk the remaining 1/2 tablespoon of taco seasoning into the ranch dressing in a small bowl.
Assemble the salad by placing the chopped lettuce in a large bowl, then topping with the beans, corn, tomatoes, and onion.
Add the sliced chicken, cheese, and crushed tortilla chips to the top of the salad.
Drizzle with the seasoned ranch dressing right before serving and toss gently.