Rinse the black lentils and place in a medium pot. Add the water followed by the cumin and salt. Bring to a boil, reduce to a simmer, cover, and cook until lentils are tender and water is absorbed, 25 minutes or so.
While the lentils are cooking, heat a large skillet over medium heat. Add the oil followed by the diced onion, pepper, and salt. Saute for 4 to 5 minutes, then add the zucchini. Cook, stirring occasionally, until the zucchini is tender and browning. Stir in the cooked black lentils, taste, and adjust salt if needed.
While the filling ingredients are cooking, combine the ingredients for the sauce in a blender. Puree until smooth.
Preheat oven to 375˚F. In a 9”x13” roasting pan or 8”x8” roasting pan, pour ⅓ of the sauce into the bottom. Assemble the enchiladas by spreading a spoonful of black lentil mixture in the center of the tortilla. Sprinkle with a tablespoon of cheese. Roll and place seam-side down. Continue with remaining black bean mixture and tortillas.