Prep the Mushrooms: Preheat your oven to 375°F (190°C). Clean the mushrooms with a damp cloth and remove the stems. Gently scrape out the gills to make space for the filling.
Cook the Filling: Heat the olive oil in a pan over medium heat. Add the ground meat and cook, breaking it apart with a spatula. Once browned, stir in the taco seasoning and black beans. Cook for another 3-4 minutes until everything is well combined.
Stuff the Mushrooms: Place the mushroom caps on a baking sheet. Spoon the taco mixture into each mushroom, pressing gently to fill. Top with shredded cheese.
Bake: Place the mushrooms in the preheated oven and bake for 20 minutes, or until the mushrooms are tender and the cheese is melted and bubbly.
Serve: Garnish with sour cream, diced tomatoes, and cilantro for a fresh touch. Serve warm.