GRILLED MEATBALL SANDWICH

Steps:

• To make the arugula pesto, in a food processor, combine the walnuts, garlic, arugula, Parmigiano-Reggiano and the 1 tsp. salt and pulse to blend. With the machine running, pour in the olive oil through the feed tube in a slow, steady stream and process until smooth, stopping to scrape down the sides of the bowl as needed. Taste and adjust the seasonings with salt. Set aside.
• In a large bowl, combine the ground beef, ricotta, Parmigiano-Reggiano, bread crumbs, eggs, parsley, garlic, red pepper flakes and salt. Mix gently just until combined; you don't want to overwork the meat. Form the mixture into 12 meatballs about the size of golf balls, putting them on a lightly oiled baking sheet as you work. Set aside at room temperature.
• Build a hot fire in a charcoal grill or preheat a gas grill to high. Using a grill brush, scrape the heated grill rack clean. Rub the rack with oil.
• Arrange the meatballs on the grill rack without crowding. Using tongs, grill until the meatballs are browned evenly on all sides and cooked to medium, 8 to 10 minutes total, depending on the grill temperature. Move any meatballs to a cooler area of the grill if they threaten to overbrown. Transfer to a platter or a clean baking sheet as they are finished. Let rest for 5 minutes while you assemble the sandwiches.
• Cut the baguette crosswise into 4 pieces and split each piece horizontally. Lay the pieces, cut side down, on the grill. Toast until golden brown, about 3 minutes. Lay the provolone slices on half of the baguette pieces. Place 3 meatballs on top of the cheese-lined baguette slices. Garnish with the pesto, cover the sandwiches with the remaining baguette pieces and serve immediately.