- 1 1/2 cups cold water
- 1/3 cup yellow cornmeal (preferably stone-ground)
- 1/4 teaspoon salt
- 2 small (2 1/2-inch-wide) tomatoes
- 1 1/2 oz smoked mozzarella, coarsely grated (1/3 cup)
- 1 cup fresh basil
- 2 tablespoons water
- 1 small garlic clove
- 1 teaspoon fresh lemon juice
- 1 teaspoon extra-virgin olive oil
- Pinch of sugar
- Special equipment: a 2 1/2-inch round cookie cutter
- Whisk together water, cornmeal, and salt in a 1-quart heavy saucepan and bring to a boil over moderate heat, whisking constantly. Reduce heat to low and cook, stirring frequently, until very thick, 15 to 20 minutes.
- Spread polenta into a 10- by 5-inch rectangle on a lightly oiled baking sheet. Chill, uncovered, until firm, about 1 hour.
- Prepare grill for cooking.
- Cut 4 (1/4-inch-thick) crosswise slices from middle of each tomato. Sandwich slices between triple thicknesses of paper towel and press gently to absorb excess moisture.
- Preheat oven to 400°F.
- Cut out 8 (2 1/2-inch) rounds from polenta with cookie cutter. When fire is medium-hot (you can hold your hand 5 inches above rack for 3 to 4 seconds), grill polenta rounds in a grill basket until crusty, about 5 minutes on each side. Transfer to an ungreased baking sheet.
- Season tomato slices with salt and pepper and sprinkle with cheese. Assemble 4 stacks by placing a tomato slice on top of each of 4 polenta rounds (use a spatula to transfer tomato slices), then top each with another polenta round and tomato slice.
- Bake in middle of oven until hot and cheese is melted, about 15 minutes.
- Purée basil, water, garlic, lemon juice, oil, and sugar in a blender, scraping down sides frequently, until smooth. Season with salt and pepper.
- Serve stacks with basil sauce.