Heat the large skillet over medium-high heat and add 2 tablespoons olive oil.
Place the bite-sized chicken pieces in the skillet, sprinkle evenly with about 1 heaping tablespoon of the taco seasoning, and cook for about 5 minutes, turning occasionally until cooked through; cooking time will vary by piece size.
Remove the skillet from the heat and let the chicken rest in the pan while you assemble the salad.
On a large platter, spread the romaine lettuce and top evenly with diced tomatoes, drained corn, drained and rinsed black beans, diced avocado, shredded cheese, crushed tortilla chips, and the cooked chicken.
In a small bowl, whisk together 1/2 cup mayonnaise, 1/4 cup sour cream, 3 to 4 tablespoons lime juice, and the remaining 1 heaping tablespoon taco seasoning until smooth.
Stir in the minced cilantro and taste the dressing; add up to 1/2 teaspoon granulated sugar if needed and more lime juice to reach desired consistency.
Drizzle the dressing evenly over the assembled salad and serve.