Set your oven to 375F and allow to preheat.
Brush the portobello mushrooms with olive oil. Ensure that all sides are coated.
Cut up the mozzarella cheese and stuff them into the mushrooms.
Sprinkle the cherry tomatoes with balsamic vinegar and season them with pepper and salt. Now place the tomatoes on the mozzarella cheese stuffed in the mushroom.
Place the mushrooms in the preheated oven and allow to bake for 20 minutes.
Serve in a plate and enjoy with a salad or mixed greens.