Mix meat, bread crumbs, water, 6 Tbsp cheese, egg, Parsley, salt, and pepper in a large bowl.
Heat vegetable oil in a large skillet over medium heat.
Add olive oil to skillet.
Add onion, garlic and basil.
Cover with lid and simmer until meatballs are cooked through, approx 20 minutes
Place arugula leaves on bottom of each roll, and top with one meatball.
Drizzle meatballs with remaining sauce and sprinkle with grated cheese