In a large skillet over medium-high heat, saute chopped onion in coconut oil until translucent. Add yam and black beans and saute until tender. Add green chilis, garlic, and seasonings and cooked for 2-3 minute more.
Remove from heat and stir in sour cream.
Steam tortillas by putting them in a tortilla warmer or wrapping them in a kitchen towel and heating them on high in the microwave for about a minute.
Put about 2 tablespoons of filling in the middle of each tortilla and fold over. Arrange in a large casserole dish.
Pour about 2 cups of sauce over top and spread evenly. Sprinkle with grated cheese.
Bake at 350° F for 30 minutes or until cheese is melted and everything is bubbly.
Garnish with fresh cilantro and serve warm, with remaining enchilada sauce on the side.
This recipe can easily be made vegan and dairy-free simple by substituting in vegan sour cream and either leaving the cheese off the top or using vegan cheese.