Mushrooms may be cooked whole, sliced or chopped. The stems of Shiitake mushrooms and the root end of Portabella stems are often tough and should be discarded or used to add flavor to sauces and stocks, but all other mushroom stems can be trimmed and used along with the caps.
Sliced or whole mushrooms can be sautéed in oil or broth for 8 - 10 minutes. Cook alone or in combination with other vegetables.
Sliced or whole mushrooms can be grilled on skewers or directly on grill for 8 - 10 minutes.
Mushrooms freeze best once they have been cooked. Just clean, trim and slice the mushrooms; sauté them in oil or butter and cool to room temperature. Then, package in airtight 1/2-cup or 1-cup containers and freeze. They may be kept several months and are best if thawed in the refrigerator before use.