1. Preheat the oven to 375°F (190°C).

2. Clean the portobello mushrooms and remove the stems. Place them on a baking sheet.

3. In a skillet, sauté chopped garlic and diced red onion until translucent. Add cooked basmati rice, black beans, mixed vegetables, and season with salt and pepper.

4. Fill each mushroom cap with the rice and vegetable mixture.

5. Top each stuffed mushroom with grated mozzarella and fresh parmesan cheese.

6. Bake in the preheated oven for 20-25 minutes until the cheese is melted and bubbly.

7. Serve hot and enjoy!