This is a very delicious, meaty dish, that looks very nice, and tastes wonderful. It's very simple and quick.
Wash a portobello mushroom, and take off the stem. Chop the stem, and slice half a small onion. Heat up a pan (Preferably cast iron) with a little olive oil, and add you cap, gill side up, and your sliced onion and stem pieces to the side. Drizzle some olive oil into the cap, and drizzle a little balsamic vinegar into the cap and onto the onions and stem. Stir the onions and stem fairly often, and check the cap occasionally, once the cap is slightly browned on the bottom, flip it over and cook until tender. Once tender place it on a plate gill side up, and top it with the stem and onion, and garnish with basil. Yum!
Oh woah! This is my hundredth post!