Bring 2 cups water to a boil in a saucepan. Add chicken, chicken bouillon, onion, and garlic. Cover and simmer until chicken is no longer pink the middle, about 40 minutes.

Meanwhile, preheat a pancake grill to 400 degrees F (200 degrees C).

Mix corn flour, 1 1/4 cups water, and salt together in a bowl until a smooth, moist dough is formed. Add more water if the dough seems too dry. Divide dough into 8 to 10 medium-sized balls and pat each into a 1/4-inch thick round.

Cook dough rounds on the preheated grill until cooked on the outside, about 3 minutes per side. Pull the edges out while still hot, making a little indention in the center of each gordita.

Heat oil in a skillet over medium heat. Deep fry gorditas until golden brown on both sides, 2 to 5 minutes per gordita. Set aside on a wire cooling rack.

Pour beans into a small saucepan and warm over medium heat.

Drain chicken, reserving cooking liquid. Remove meat from the bones and transfer meat to a food processor. Add a few tablespoons of cooking liquid and chop to desired consistency.

Spread a layer of warm beans on each gordita, then top with chopped chicken, lettuce, tomato, avocado, and cotija cheese. Finish with a dollop of sour cream.