Poach the chicken by placing it in a large pot with onion, carrots, celery, garlic, peppercorns, and parsley. Cover with cold water and add sea salt.
Bring the pot to a boil, then reduce the heat to medium-low. Simmer for about 1.5 hours, skimming off any foam.
Remove chicken from the pot and let it cool. Shred the meat once cooled, discarding the bones and skin.
Preheat your oven to 350°F and warm the tortillas in a bit of oil so they are pliable for rolling.
Fill each tortilla with shredded chicken and a spoonful of enchilada sauce. Roll them up and place in a baking dish.
Pour the remaining enchilada sauce over the rolled tortillas and sprinkle with shredded cheese.
Bake in the preheated oven for 20 minutes or until the cheese is melted and bubbly.