1/3 cup finely chopped fresh basil  | 
                                                2 tablespoons dijon mustard  | 
                                                2 tablespoons honey  | 
                                                2 teaspoons grated lemon rind  | 
                                                1/4 cup fresh lemon juice  | 
                                                1 tablespoon extravirgin olive oil  | 
                                                1/2 teaspoon salt  | 
                                                1/4 teaspoon freshly ground black pepper  | 
                                                4 garlic cloves, minced and divided  | 
                                                1 pound firm or extrafirm tofu, drained  | 
                                                cooking spray  | 
                                                1/3 cup finely chopped pitted kalamata olives  | 
                                                3 tablespoons reduced-fat sour cream  | 
                                                3 tablespoons light mayonnaise  | 
                                                6 (1 1/2-ounce) hamburger buns  | 
                                                6 (1/4-inch-thick) slices tomato  | 
                                                1 cup trimmed watercress  |