Preheat oven to 400 degrees
Combine chicken, 1 cup salsa verde, beans (rinsed and partially smashed), 1/4 cup cilantro, salt and pepper to taste.
Spread 1 cup of salsa verde in bottom of a 9x13 baking dish.
Warm tortillas in a skillet, or wrap them in damp paper towels and microwave on high power until warm and pliable.
Spoon about 1/4 cup of chicken filling into each tortilla, sprinkle with cheese and roll into a cylinder, place seam side down in baking dish. Repeat with remaining filling and tortillas.
Drizzle enchiladas with 1 1/2 cups salsa verde.
Cover dish with foil and bake at 400 degrees for 30 minutes.
Remove from oven, remove foil, and immediately sprinkle with remaining cheese (and onion if desired), let stand for a few minutes until cheese has melted.
Serve with sour cream and remaining salsa verde.