Some good recipes for sautéed portabello mushrooms are The Dr. Oz Show's sautéed portabello mushroom recipe and Made Man's sautéed portabello recipe. The Dr. Oz Show's recipe uses whole portabello mushrooms with the stems removed, and Made Man's recipe works with whole, chopped or sliced portabellos.
Prepare The Dr. Oz Show's sautéed portabello mushroom recipe by adding 1/2 small onion, diced, to a large frying pan with a thin layer of broth or water. After 2 minutes, add 1 cup broth and a splash of some balsamic vinegar and mirin or sherry. Add the two portabello caps, and cook for 5 minutes. Flip and cook an additional 5 minutes, and add broth to prevent sticking. Serve with pan juices dripped over the mushrooms.