In a large frying pan over high heat, heat oil. Add mushrooms, sprinkle with salt and pepper to taste, and sauté, stirring often, 5 minutes.
Add garlic and thyme and cook, stirring, until mushrooms are nicely browned, 3 to 4 minutes. Stir in lemon juice to brighten the flavor.
Note: Nutritional analysis is per 1/4-cup serving.