- Set out a baking sheet and set temperature of oven at 300 F.
- Place bread slices on a flat working surface. Cut into 1.5-inch rounds using a small cookie cutter or knife.
- Arranged in a single layer on baking sheet and toast in oven for about 15 to 20 minutes or until lightly browned, turn on both sides.
- Combine ground beef, egg yolk, onion, salt and pepper. Mix lightly.
- Shape into balls about 3/4 inch in diameter. Place on toast rounds and flatten meat to the edges of toast.
- Make an identification in the center of each burger; fill with 1/4 teaspoon of ketchup.
- Set the temperature control to broil.
- Set burgers on broiler rack and place in broiler with top of meat about 3 inches from heat source. Broil for about 4 minutes or until done.
- Garnish with coriander leaves. Serve hot.