Pork Shashlik With Spicy Red Wine Marinade

Name: Pork Shashlik With Spicy Red Wine Marinade
Ingredients: 4 garlic cloves, minced; 4 plum tomatoes, coarsely grated on a box grater; 1 medium onion, coarsely grated on a box grater; 1 cup dry red wine; 1/4 cup chopped cilantro, plus cilantro sprigs for garnish; 1 teaspoon crushed red pepper; 1 teaspoon dried oregano; 1 teaspoon paprika; 4 pounds trimmed boneless pork shoulder, cut into 2-inch pieces; Vegetable oil, for brushing; Salt and freshly ground pepper; Grilled flatbread, for serving