Preheat oven to 350°F (176°C).
Heat 1/2 Tbsp. coconut oil in a skillet. Add chopped onion and peppers and sauté 4-5 minutes on medium-high heat until onions are translucent and peppers are starting to get brown spots. Remove peppers and onions to a large bowl and set aside.
Flatten chicken breasts by either slicing in half long-ways or by pounding the thickest parts with a meat pounder or wooden spoon. Season chicken breasts with salt and pepper.
Melt remaining 1/2 Tbsp. coconut oil in the same pan that was used for the onions and peppers. Add chicken breasts to pan and cook for 5-7 minutes over medium heat.
Flip and cook for 5-7 minutes longer until chicken is cooked through but still tender. Remove from stove and shred using two forks.
Add shredded chicken, black beans, cumin, sour cream, and salsa to bowl with the onions and peppers. Stir to combine. Season to taste with salt and pepper.
Briefly warm the tortillas by either placing in the microwave for 30 seconds or the oven for 2 minutes. Meanwhile, spoon about 1/4 to 1/3 cup of enchilada sauce into a 9 X 13" casserole dish.
Add 1 - 1.5 Tbsp. of cheese to a tortilla and top with about 1/2 cup of chicken mixture. Fold one side over the other as shown in the pictures. Place seam side down in prepared baking dish. Repeat with remaining tortillas.
Spoon remaining enchilada sauce over the rolled tortillas and top with remaining cheese. Bake for 20 - 30 minutes until cheese is melted and the middle is warm.