Prepare mushrooms by tearing each into strips (in half if small, into quarters if big). Put a sauté pan on high heat, add olive oil, and toss in mushroom strips. Cook for 2 to 3 minutes, shaking or stirring often, or until shrooms begin to release their liquid and some pieces start to brown. Remove and set aside to cool. (To double or triple recipe, roast shrooms for 6 minutes on a tray in a 350° F oven instead of on stove.)