Open-faced Grilled Eggplant Sandwiches ¼ cup extra-virgin olive oil1 teaspoon coarse sea salt¼ teaspoon cayenne½ teaspoon freshly ground black pepper1 medium-size eggplant (about 1 pound), sliced into 1/2-inch rounds2 medium-size red onions, sliced into 1/2-inch rounds4 heirloom tomatoes, cut crosswise into 1/2-inch slices1 loaf of rustic bread cut diagonally into eight 1/2-inch slicesFreshly ground white pepperFine sea salt SAUCE½ pound silken tofu2 tablespoons freshly squeezed lemon juice2 tablespoons minced fresh parsley1 garlic clove, minced½ teaspoon agave nectar½ teaspoon Dijon mustard2 tablespoons extra-virgin olive oil½ teaspoon paprika¼ cup minced green onions (green and white parts)½ cup loosely packed peeled and coarsely grated celery root (celeriac)A few pinches of cayenneCoarse sea saltFreshly ground white pepper For the sandwiches: Preheat a grill or broiler. Soak eight 12-inch wooden skewers in water for at least 30 minutes. In a mixing bowl, combine the olive oil, salt, cayenne, and black pepper and mix well with a fork.