Simple Marinated Mushroom Salad

Ingredients

• 1 tablespoon white wine vinegar
• 1 tablespoon Dijon mustard
• 1/4 teaspoon dried oregano
• 1/4 teaspoon dried tarragon
• 1/8 teaspoon salt
• 1/8 teaspoon pepper
• 2 to 4 tablespoons olive oil
• 1-1/2 cups sliced fresh mushrooms
• 1/2 cup cherry tomatoes, halved
• 8 pitted ripe olives, halved
• Lettuce leaves