Prep: 15 minutes.
1. In a small bowl, combine beans, garlic powder, and cumin; set aside.
2. Assemble the salads by dividing the lettuce evenly among 4 shallow bowls or dinner plates. Sprinkle each serving with the bell pepper; then divide the reserved beans among plates. Divide cheese and next 3 ingredients (through scallions) among plates, and garnish each plate with 6 tortilla chips.
3. Prepare the dressing by stirring together the salsa and sour cream in a small bowl. Add a 1/4-cup dollop of dressing to each portion of salad, or pass the dressing separately.