Ingredients

• 4 roma tomatoes, halved lengthwise and seeded
  
• 1 tablespoon balsamic vinegar
  
• 1/4 teaspoon freshly ground black pepper
  
• 1/8 teaspoon salt
  
• 1/3 cup extra-virgin olive oil
  
• 2 tablespoons balsamic vinegar
  
• 1 teaspoon snipped fresh herb (basil, marjoram, oregano, rosemary, tarragon, or thyme)
  
• 1/4 teaspoon salt
  
• 1/8 teaspoon freshly ground black pepper
  
• 6 cups mesclun or torn mixed salad greens
  
• 1 cup sliced fresh cremini or button mushrooms
  
• 1/2 cup seedless red and/or green grapes, halved
  
• 1/4 cup coarsely chopped walnuts, toasted