Toss the chicken. In a bowl, mix the leftover chicken with 1/3 cup BBQ sauce until evenly coated. Add a pinch of salt and pepper if needed. If the chicken is cold and firm, warm it gently in a pan for 1–2 minutes to loosen the texture.
Make the dressing. Whisk yogurt or mayo, BBQ sauce, lime juice, olive oil, honey, garlic powder, salt, and pepper.
Taste and adjust. You want it tangy-sweet with a smoky finish.
Prep the veggies. Chop the greens, halve the tomatoes, slice the onion, dice the avocado, and rinse the black beans. If using corn, quickly sear it in a dry skillet for a charred flavor.
Build the base. In a large bowl, add greens, tomatoes, corn, onion, black beans, and cilantro.
Drizzle over half the dressing and toss lightly to coat.
Add the chicken. Scatter the BBQ chicken on top. Add cheese and jalapeños if you like a kick.
Finish and serve. Top with avocado and crushed tortilla chips. Drizzle with a little more dressing and an extra thread of BBQ sauce.
Serve right away.