Slow Cooker Beef Stew

Name: Slow Cooker Beef Stew
Ingredients: 2 pounds chuck roast , cut into 1-inch chunks; 1/4 cup all-purpose flour; 1 teaspoon salt , plus more to taste; 1/2 teaspoon ground black pepper , plus more to taste; 2 tablespoons olive oil; 1 medium white onion , chopped; 1 cup dry red wine , like Cabernet Sauvignon; 3 stalk celery chopped; 2 medium parsnips , peeled and chopped; 4 medium carrots , peeled and chopped; 1 pound new potatoes , halved; 3 cloves garlic , quartered; 2 bay leaves; 4 cups beef stock; 2 tablespoons cornstarch; 2 tablespoons water; Chopped fresh parsley leaves , for garnish