PORTOBELLO BURGER: Preheat a grill or grill pan. Whisk together 1 clove garlic (minced), ½ tbsp. balsamic vinegar, 1 tbsp. olive oil, and ½ tsp. fresh basil (finely chopped). Drizzle half the sauce over 1 Portobello mushroom cap. Grill the mushroom for 3 to 4 minutes per side, covered. Meanwhile, combine the remaining sauce with ½ tbsp. light mayo and spread on 1 whole-wheat bun (lightly toasted). Place the mushroom cap, 1 tomato slice, and 1 lettuce leaf on the bun.