Start by adding a quart of cold water to a mixing bowl along with a 1/4 cup of Kosher or sea salt. Dissolve the salt and then add the chicken breasts. Let the chicken brine for 30-60 minutes. I usually cover the bowl and put it in the fridge. Once brined you can pat the chicken dry and add it to a baking sheet.
Rinse and de-stem the tomatillos. Add them to the same baking sheet as the chicken and bake for 20 minutes in a 400F oven. For this batch I also roasted the jalapenos and 1/2 onion but that is optional.
When the chicken is no longer pink inside or registers 160-165F then it's done. Set aside to cool and then shred using two forks.
In a blender add the following ingredients: the roasted tomatillos, 1-3 jalapenos, 1/2 onion, 3-4 peeled garlic cloves, and 10-15 sprigs of cilantro. Combine well and take a taste for heat, adding more jalapeno for more heat.
Add the green sauce to a pan along with 1/2 cup of stock and 1 teaspoon Mexican oregano, bringing it up to temp over medium-low heat. Take a final taste for seasoning.
Heating up the corn tortillas first will make them easier to roll. I covered them with a damp paper towel and nuked them for 60 seconds. You could also flash fry them or heat them up in the oven.
Add a thin layer of green sauce to your baking dish to prevent sticking. Put some green sauce on a plate, dredge a tortilla in it, then flip it and fill with your preferred ingredients. I used the shredded chicken, plenty of Jack cheese, and some finely chopped raw onion. Roll tight and place seam side down in the baking dish. Continue until all the hcicken is gone.
Cover the enchiladas with plenty of green sauce and a layer of shredded cheese. Bake for 8-10 minutes in a 400F oven.
Serve immediately with your choice of garnish. Freshly chopped cilantro, a squeeze of lime, and more green sauce are all good options.