- 1 large red onion
- 2 pounds ground beef
- 3/4 cup dried tomato and arugula pesto, or to taste
- 6 ounces mozzarella, cut into 6 slices
- olive oil for brushing onion
- 6 hamburger buns, grilled lightly if desired
- 1 1/2 cups packed arugula, washed well and spun dry
- 1/3 cup drained bottled dried tomatoes packed in oil
- 1/4 cup olive oil
- 3 tablespoons freshly grated Parmesan
- 2 tablespoons pine nuts, toasted golden and cooled
- 1 large garlic clove, chopped and mashed to a paste with 1/2 teaspoon salt
- a pinch sugar
- Prepare grill.
- Cut six 1/4-inch-thick slices from center of onion and reserve. Divide beef into 6 portions. Form indentation in each portion and spoon rounded teaspoon pesto into each indentation. Form beef portions into six 3/4-inch-thick patties, enclosing pesto completely. Grill patties on an oiled rack set 5 to 6 inches over glowing coals 5 minutes. Turn burgers and grill 3 minutes more. Top burgers with mozzarella and grill 2 minutes more, or until just cooked through. Transfer burgers to a platter and let stand while grilling onion. Brush onion on both sides with oil and grill until softened and browned, about 3 minutes on each side.
- Spread pesto on both sides of buns and make sandwiches with onion and burgers.
- In a food processor blend together all ingredients with salt and pepper to taste until smooth. Pesto keeps, surface covered with plastic wrap, chilled, 1 week. Makes about 1 cup.