- 1 pound ripe green heirloom tomatoes, cored, cut into large chunks
- 1 6-inch piece unpeeled English hothouse cucumber, diced
- 1/2 cup chopped onion
- 1/2 cup chopped celery
- 1/2 cup salted roasted Marcona almonds
- 2 tablespoons extra-virgin olive oil
- 2 large garlic cloves, peeled
- 1 tablespoon Champagne vinegar or other white wine vinegar
- 1 teaspoon (or more) coarse kosher salt
- 8 1/3-inch-thick slices brioche or challah, trimmed to 5×3 inches
- 1 8-ounce package smoked mozzarella cheese, cut into 1-inch-wide by 1/8-inch-thick slices
- 2 large heirloom tomatoes (preferably Brandywine), cut into 1/4-inch slices
- 1/4 cup (1/2 stick) butter
- Combine first 8 ingredients and 1 teaspoon coarse salt in processor. Blend to almost smooth puree (some texture should remain). Season with pepper and more salt, if desired. Transfer to medium bowl. Cover; chill at least 3 hours and up to 1 day.
- Cut each bread slice into rectangle (about 4 1/2 x 2 1/2 inches). Arrange 4 bread rectangles on work surface. Top bread with half of cheese slices (trimming to fit) and 2 tomato slices. Sprinkle tomatoes with salt and pepper. Top with remaining cheese, then remaining bread; press to compact.
- Melt butter in large skillet over medium heat. Add sandwiches. Cover and cook until bread is golden, turning once, about 3 minutes per side. Transfer sandwiches to paper towels. Cut each sandwich in half.
- Divide gazpacho among 4 bowls; place on plates. Arrange sandwiches alongside.