For slicing or chopping large quantities, use a food processor with the slicing or wing blade attachment. If a recipe calls for just caps, twist stems loose or separate them from the caps with the tip of a knife. For each eight ounces of mushrooms, melt one tablespoon butter or heat one tablespoon of oil in a large skillet. Cook and stir until golden and the released juices have evaporated, about five minutes. Don't overcrowd the skillet or the mushrooms will steam rather than brown.
Mushrooms cook extremely well in the microwave.
Toss with a little oil and roast in a 450 F oven, stirring occasionally until brown, about 20 minutes. Use about one tablespoon of oil for each eight ounces of mushrooms. Lightly brush caps and stems with oil to keep them moist, and season with salt and pepper. Grill or broil 4 to 6 inches from heat source for 4 to 6 minutes on each side, brushing again once or twice. Virtually any and all seasonings go well with mushrooms.