Using the flat side of a meat mallet, flatten chicken breasts between two pieces of plastic wrap until 1/2 inch thick.
In a shallow dish or pie dish, lightly beat together egg and the water. Place flour in another shallow dish. In a third shallow dish combine bread crumbs, chili powder, garlic powder, onion powder, kosher salt, and pepper. Dip each chicken breast in the egg mixture, then in flour to coat. Dip in egg mixture, then in crumb mixture to coat until.
In a 12-inch cast-iron skillet heat oil over medium. Add the chicken. Cook 12 to 16 minutes or until a meat thermometer reaches(165°F). In the last couple minutes of cooking, top each chicken breast with 1 tbsp of the Queso fresco. Cover the skillet with a baking sheet if need be to melt the cheese.
In a small bowl combine chipotle peppers, adobo sauce, and mayonnaise. Spread tops of buns with chipotle mixture. Fill buns with chicken, onion slices, and pickles. Serve and enjoy!