In another pot, bring the tomatillos, serrano peppers, garlic clove, and a quarter of the onion to a boil over high heat. Once it starts boiling, cook for one more minute, then turn off the heat and let cool for three minutes.

Once the tomatillos and peppers have cooled, blend them with the cooked garlic, onion, chicken bouillon cube, 1 cup water (about 240 ml), and salt to taste. Fry the sauce in a skillet with 1 teaspoon vegetable oil for 10 minutes. Turn off the heat and set aside.

Shred the cooked chicken breast and mix in a little of the sauce.

Warm the tortillas in the microwave for about 1 minute or until soft and hot. Assemble the enchiladas by filling each tortilla with chicken, rolling them up, and placing them on a plate with a little space between each. Pour the sauce over the enchiladas and garnish.

Slice the remaining onion into rings and place on top of the enchiladas along with the queso fresco and sour cream.