*Using a very small Linzer-style heart-shaped cutter, cut 24 shapes from approximately 4 large roasted red pepper pieces. If doing these in advance, up to a day, store pepper hearts in liquid from jar in a container in the refrigerator. Drain and blot dry on paper towels before using.
Make-Ahead Tips: Bread rectangles can be cut up to a day in advance and stored in a resealable plastic bag at room temperature. Beef can be cooked up to a day in advance, wrapped tightly in foil, and refrigerated. Slice and serve cold or at room temperature. Sandwiches can be assembled up to an hour in advance, covered with damp paper towels, placed in an airtight container, and refrigerated. Garnish just before serving.