Preheat the oven to 425 degrees. Coat a muffin tray with cooking spray.
Prepare the chicken mixture by chopping the chicken then combine it with the beans/rice, the cotija cheese, green onion, cilantro, juice from 1/2 a lime, sour cream, and salsa. Mix until evenly combined, taste then season with sea salt and freshly cracked pepper, to taste.
Make the taco cups by using a biscuit cutter (or a ramekin & a knife) to cut out small circles from the large flour tortillas. Carefully place the flour tortilla circles into the muffin tray.
Fill the taco cups by adding a spoonful of refried beans into each cup followed by a bigger spoonful of the chicken mixture. Top each cup with a small about of cheddar cheese.
Bake the taco cups by placing them into the oven and bake for 15-20 minutes, or until heated through and the tortillas are crisp.
To serve, garnish the top with sour cream, avocado, tomato, green onion, and cilantro. Serve with salsa and hot sauce, if desired. Enjoy.