To make grilled portobello mushrooms, clean the mushrooms and remove the stems. Marinate them in a mixture of 1/4 cup of canola oil, 3 tablespoons of finely minced onion, 4 cloves of finely minced garlic and 1/4 cup of balsamic vinegar for one hour, and grill over high heat for 10 minutes turning occasionally. Modify this basic recipe by adding additional favorite herbs to the marinade.
Grilled portobello mushrooms are a good meal alternative for vegetarian guests at a barbecue. They also substitute nicely for burgers when served on a bun with toppings. Try slicing the mushrooms and serving them on top of a salad or pasta dish for a vegetarian main course.
A gallon-size resealable plastic bag makes a nice container for marinating the mushrooms. Simply shake the bag to redistribute the marinade. Keeping the mushrooms gill-side up with most of the marinade on the gills helps it to settle into the nooks to better flavor the mushrooms. Lemon juice makes a nice alternative to balsamic vinegar in this recipe, or substitute extra-virgin olive oil for the canola oil and 1 tablespoon of Dijon mustard for part of the balsamic vinegar for a nice flavor change. Sprinkle the finished mushrooms with fresh chopped herbs or finely diced dried tomatoes.