Source: Cooks Illustrated

Ingredients
3 pounds boneless long-cut beef shanks
Salt and pepper
5 garlic cloves, peeled and smashed
5 allspice berries
4 bay leaves
1.5 teaspoons peppercorns
2 large onions, halved and sliced
2.25 cups dry white wine
0.25 teaspoon ground cinnamon
8 ounces Spanish-style chorizo sausage, cut into 1/4-inch-thick rounds


Directions
Adjust oven rack to middle position and heat oven to 325 degrees. Trim away any fat or large pieces of connective tissue from exterior of shanks (silverskin can be left on meat). Cut each shank crosswise into 2 1/2-inch pieces. Sprinkle meat with 1 teaspoon salt.
Cut 8-inch square of triple-thickness cheesecloth. Place garlic, allspice berries, bay leaves, and peppercorns in center of cheesecloth and tie into bundle with kitchen twine. Arrange onions and spice bundle in Dutch oven in even layer. Add wine and cinnamon. Arrange shank pieces in single layer on top of onions. Cover the pot tightly with aluminum foil and pot lid and cook until beef is tender, about 3 1/2 hours.
Remove pot from oven and add chorizo. Using tongs, flip each piece of beef over, making sure that chorizo is submerged. Cover and let stand until chorizo is warmed through, about 20 minutes. Discard spice bundle. Season with salt and pepper to taste. Serve.