Pressed Picnic Sandwich

Name: Pressed Picnic Sandwich
Ingredients: 3 medium red bell peppers; 1 ½ teaspoons Dijon mustard; 1 tablespoon balsamic vinegar; ¼ cup extra-virgin olive oil; 2 tablespoons warm water; Kosher salt and freshly ground pepper; 1 loaf ciabatta (1 pound, about 6 inches wide); ½ cup prepared black-olive paste; 4 ounces fresh goat cheese; 8 ounces marinated artichoke hearts, drained; 6 ounces prosciutto, thinly sliced; 4 ounces spicy salami, thinly sliced; 2 cups loosely packed mixed fresh herbs, such as basil, cilantro, or parsley