Ingredients

  • 1 cup mayonnaise
  • 1/3 cup shopped fresh basil
  • 2 tablespoons Dijon mustard
  • 1 teaspoon fresh lemon juice
  • 1/3 cup olive oil
  • 1 tablespoon minced garlic
  • 1 1/2 cups mesquite wood chips, soaked in cold water 1 hour (optional)
  • 6 4- to 5-inch-diameter portobello mushrooms, stems removed
  • 6 3 1/2- to 4-inch-diameter whole-grain hamburger buns, split
  • 6 large romaine lettuce leaves
  • 6 large tomato slices

Method

  • Mix first 4 ingredients in small bowl.
  • Season with salt and pepper.
  • Whisk olive oil and garlic in another small bowl.
  • Prepare barbecue (medium-high heat).
  • When coals turn white, drain chips, if using, and scatter over coals.
  • When wood chips begin to smoke, brush mushroom caps on both sides with garlic oil.
  • Season with salt and pepper.
  • Grill mushrooms until tender and golden brown, about 4 minutes per side.
  • Transfer to platter; cover with foil to keep warm.
  • Grill cut side of hamburger buns until light golden, about 2 minutes.
  • Place bottom half of hamburger bun on each plate.
  • Top each with 1 mushroom, then 1 lettuce leaf and 1 tomato slice.
  • Spoon some basil-mustard sauce over tomato and top with bun.
  • Pass remaining basil-mustard sauce separately.