In a large skillet, heat a tablespoon of oil over medium heat. Add the diced onion and bell peppers, sautéing until soft (about 5 minutes). Stir in the minced garlic, cumin, and chili powder; cook until fragrant (another 2 minutes).

Add the cooked lentils and corn to the skillet. Stir well to combine all the ingredients, seasoning with salt and pepper to taste. Let this simmer for about 3-4 minutes to allow the flavors to meld.

Preheat your oven to 375°F (190°C). Spread a layer of enchilada sauce at the bottom of a baking dish.

Take a tortilla, fill it with the lentil mixture, and roll it up tightly. Place seam-side down in the baking dish. Repeat until all tortillas are filled.

Once all enchiladas are in the dish, pour the remaining enchilada sauce over the top. If desired, sprinkle with cheese.

Cover the dish with foil and bake for 20 minutes. Remove the foil and bake for an additional 10 minutes, or until the sauce is bubbly and cheese is melted if using.

Remove from the oven, let it cool for a few minutes, and garnish with fresh cilantro before serving.