Heat the oil in a large skillet over high heat. When the oil is hot, add the mushrooms, salt, and pepper, and sauté until the mushrooms are wilted, for about 2 minutes. Remove from the heat.
Turn the mushrooms into a bowl, add the green onions and bell peppers, and toss until thoroughly blended. Serve at room temperature.
Yield 2 cups, 4 salad servings