Snip a tiny corner from bag with mustard. Squirt on hamburgers and hot dogs. Squirt red gel for ketchup. Squirt triangles of red gel on tomato slices. Use tip of a toothpick to pick up and drop sesame seeds in place for tomato seeds.
Place tomatoes on lettuce along with onion slices.
Thread marshmallows on poultry skewers. Lightly toast on stovetop. Cool, then place on grill.