Dutch Brisket with Braised Onions

Name: Dutch Brisket with Braised Onions
Cuisine: American
Ingredients: 1 beef brisket (6 to 7 pounds); 1 bottle (25.4 ounces) dry red wine; 1 cup tarragon wine vinegar; 4 celery ribs, coarsely chopped; 1 large onion, coarsely chopped; 6 peppercorns, crushed; 1 bay leaf; 2 sprigs fresh thyme; Salt and freshly milled black pepper; Salt and freshly milled black pepper; All-purpose flour; ¼ teaspoon ground cinnamon; ½ teaspoon ground cloves; 4 pounds yellow onions, thinly sliced; 4 tablespoons butter