Meatloaf is delicious warm or cold. These sandwiches came to us courtesy of Ford Roberts of Las Vegas, Nevada.
Preheat oven to 375 degrees. In a medium bowl, combine chopped onion, garlic, parsley, egg, and 1/3 cup ketchup. Add breadcrumbs, beef, and pork. Season with 1 1/2 teaspoons salt and 1/2 teaspoon pepper. Mix until well combined.
Place mixture in a 6-cup capacity loaf pan (8-by-4-inch). Pat gently to form a rounded top; do not pack.
Bake meatloaf 50 minutes. Remove from oven; brush with remaining 1/3 cup ketchup. Return to oven; bake until an instant-read thermometer inserted in center of loaf registers 160 degrees, 10 to 20 minutes. Cool meatloaf 10 minutes in pan before removing.
Cut warm or cold meatloaf (see note) into 6 portions; place one on each of 6 slices of bread. Layer with lettuce and red onion, if using, and top with another slice of bread. Serve with additional ketchup, if desired.
Meat loaf is delicious warm or cold. To chill, turn onto a cooling rack, right side up, until no longer hot. Wrap tightly in plastic; refrigerate until cold, two hours or up to three days.