Preheat the oven to 400 degrees F. Set a wire rack on a rimmed baking sheet and set aside. With a spoon, gently scoop out the gills that are inside the Portobello mushrooms. Discard the gills and set the mushrooms aside.

In a large skillet, heat the olive oil over medium high heat. Add the onion and red pepper. Sauté until vegetables are tender, about 5 minutes, stirring occasionally. Add the garlic and cook for one more minute. Stir in the corn, black beans, chili powder, cumin, paprika, salt, pepper, lime juice, and cilantro.

Add the enchilada sauce and stir until combined. Stir in ½ cup of the shredded cheese.

Divide the enchilada filling between the Portobello mushrooms. Top each mushroom remaining shredded cheese.

Place the mushrooms on the wire rack and bake for 20-25 minutes or until the cheese is melted and mushrooms are tender. If you want to brown the cheese on the top, put the pan under the broiler for 1 minute. Make sure you watch the mushrooms closely; the cheese will brown quickly. Remove from the oven and garnish with cilantro, avocado or guacamole. Season with salt and pepper. Serve warm.