French Country-Style Peas

1/2 cup diced onion (1 medium)
1 cup sliced fresh mushrooms (about 2 1/2 ounces)
1 package (10 ounces) frozen peas and pearl onions
1/2 teaspoon salt
1/4 teaspoon white pepper
1 cup shredded romaine or Bibb lettuce
1 tablespoon minced fresh or 1 teaspoon dried tarragon or mint leaves, crushed
1. Cook onion in water 1 minute, stirring occasionally. Stir in mushrooms and frozen vegetables; cook 3 minutes, stirring frequently. Stir in salt and pepper.
2. Stir in lettuce; cook 1 minute, stirring constantly, until lettuce is wilted. Sprinkle with tarragon