GUINNESS BEEF STEW

2 tbsp. olive oil 3 lb. beef chuck roast, well trimmed and cut into 2-inch pieces Kosher salt and freshly ground black pepper 2 medium onions, cut into 1-inch thick wedges 4 cloves garlic, chopped 1 lb. medium carrots, cut into 1-inch pieces 12 oz. medium parsnips, cut into 1-inch pieces 3 tbsp. all-purpose flour 1 (14.9-ounce) can Guinness Extra Stout or other stout beer (about 2 cups) …