Osso Buco Stew with Spicy Polenta

Name: Osso Buco Stew with Spicy Polenta
Ingredients: 3 tablespoons canola oil; 1 1/2 pounds veal stew meat; Kosher salt and freshly ground black pepper; 1/4 cup all-purpose flour; 1 (15-ounce) can chicken broth or stock; 1 medium onion, chopped; 3 stalks celery, chopped; 2 large carrots, sliced; 1 (15-ounce) can diced tomatoes; 1 tablespoon chopped garlic; 4 sprigs thyme, plus leaves for garnish; 1 (8-ounce) package polenta; 1 teaspoon red pepper flakes, 1/2 teaspoon if you like it less spicy; 1/4 cup grated Parmesan; 2 tablespoons butter