6 oz. ground beef
4 oz. sweet Italian sausage, casing removed
2 tbsp. onion, chopped finely
1/2 tsp. Italian herb seasoning
4 4-oz. slices whole-milk mozzarella cheese
1 tbsp. olive oil
2 sourdough hamburger buns
1/4 c. warm pizza sauce
Combine first four ingredients in a bowl.
Form two patties about 1 inch thick.
Grill patties about 5 inches from coals, about 6 minutes per side, until cooked throughout.
Top each burger with two slices of mozzarella about 30 seconds before removing burgers from the grill.
Brush olive oil on the inside of each hamburger bun and lightly toast on grill until golden.
Put 1/8 c. of warm pizza sauce in each hamburger bun. Then place the burger in the bun.