Preheat your oven to 375°F and lightly grease a small baking dish.
Season the chicken breast with salt and pepper, then grill or sauté until fully cooked. Once cooled, shred or dice the chicken into bite-sized pieces.
In a small bowl, mix the black beans with the shredded chicken to form the filling.
Warm the corn tortillas on a skillet over medium heat to make them pliable.
To prepare the salsa verde, roughly chop the tomatillos, jalapeno, and onion. Combine them in a blender with cilantro, lime juice, and olive oil. Blend until you achieve a slightly chunky salsa texture.
Assemble the enchiladas by spooning an even layer of the chicken-black bean mixture onto each tortilla. Roll them up tightly and place them seam-side down in the baking dish.
Pour the freshly blended salsa verde evenly over the enchiladas, ensuring they are well-covered.
Bake in the preheated oven for 15-20 minutes, allowing the flavors to meld and the edges to crisp up slightly.
Serve warm and enjoy your delicious, protein-packed enchiladas with a burst of fresh salsa verde.