Like most mushroom cooking mistakes ... America's Test Kitchen tried out the theory, steaming the cap of a portobello mushroom alongside a piece of zucchini and beef tenderloin.

Once your grill pan is hot, carefully place your marinated portobello mushroom steaks directly on the hot grill pan, with the smooth part of the mushroom cap facing up first. Cook over medium-high ...

4 Portobello caps extra virgin olive oil balsamic vinegar sea salt Preheat oven to 375 F. Place mushroom caps open side up in a shallow baking dish. Brush with olive oil, drizzle with balsamic ...