Prep the tortillas: Heat 1 tablespoon oil in a large skillet over medium heat. Working one at a time, fry each tortilla for about 30 seconds per side until pliable and lightly golden. Lay them on paper towels to drain excess oil. This step prevents soggy enchiladas — don't skip it.
Make the filling: In a large bowl, combine the shredded chicken (or beans), sour cream, cumin, garlic powder, and 1/2 cup of the cheese. Season with salt. If using beans, mash them slightly so they hold together when rolled. Set aside.
Prepare the sauce base: In the same skillet or a separate saucepan, melt butter over medium heat. Whisk in flour and cook for 1 minute until golden. Slowly whisk in milk until smooth and thickened, about 2-3 minutes. Stir in the enchilada/salsa.
Assemble: Preheat oven to 375°F (190°C). Spread a thin layer of sauce on the bottom of a 9x13 baking dish. Fill each tortilla with about 1/4 cup filling, roll tightly, and place seam-side down in the dish. Pour remaining sauce over the top and sprinkle with remaining cheese.
Bake: Cover with foil and bake for 20 minutes. Remove foil and bake another 10-15 minutes until cheese is bubbly and golden. Let rest 5 minutes before serving.
