Heat oil in a large skillet over medium heat. Add onion and garlic and saute 2 minutes. Add chicken and saute 5 minutes, until golden brown and cooked through. Remove half of the chicken and reserve for another use.
Stir in black beans, green chiles, and salsa and simmer 5 minutes, until sauce thickens and reduces. Remove from heat and stir in cilantro.
Arrange 4 tortillas on a flat surface. Top each tortilla with an equal amount of chicken mixture. Roll up tortillas and place side by side in a shallow baking dish. Top tortillas with shredded cheese (1/3 cup per tortilla).
Bake enchiladas 15 minutes, until cheese is golden and gooey!
This is enough chicken to make this meal and another meal. If you are only making this meal, use 1 pound chicken.