Combine the cornstarch, cumin, and garlic salt in a shallow dish and set aside.
Beat the egg along with the water and place in a shallow dish.
Put the cornmeal in a shallow dish.
Coat the chicken in the cornstarch mix, followed by the egg mixture, and finally coat with the cornmeal.
Heat the oil in a skillet over medium-high heat and place the chicken in it in a single layer, cooking about 4 minutes on each side.
Remove the chicken from the skillet and place in a shallow baking dish.
Cut the avocado in half (removing the pit of course), and then cut into quarters.
Finally cut the avocados into slices about 1/4-1/2 inch wide (I like to have at least 3 slices for each chicken breast.) Place the avocado slices over the chicken and then sprinkle the cheese evenly over the chicken.
Bake for about 15 minutes or until the cheese is well melted.
Serve each piece with about a tsp of sour cream on top and sprinkled with the chopped scallions and bell peppers.