Preheat the oven to 350 degrees F. To make the guacamole, place the avocado and lime juice in a bowl and mash well. Mix in the sour cream and salsa. Store in the fridge until needed. Mound half the tortilla chips on a heatproof platter or non-stick pizza pan. Top the tortilla chips with 1/2 the cheese, bell pepper, chicken and black beans. Mound the rest of the chips on the pan; top with the remaining cheese, bell pepper, chicken and black beans. Bake for 10 minutes, or until the cheese is melted and the chips are heated through. Sprinkle with green onions and serve with the guacamole for dipping.
Note: Cooked, cold barbecue chicken legs are available in the deli department. Use any leftover black beans from the can in another dish, such as a salad, chili or soup.