Chop the beef shank into large chunks, keeping some attached to the bone, as bone marrow is an important element of the dish. Saute the beef chunks with the chopped onions, salt, and pepper. After beef is browned, add the beef stock and the stewed tomatoes. Bring the mixture to a boil and then simmer just below boiling point for about one hour, until the beef is "spoon tender."
Wash the vegetables. Cut each ear of corn and each potato into quarters. Cut equivalent chunks of carrots and chayote (if zucchini is used, keep pieces bigger as they will cook faster than chayote). Add the vegetables to the soup. Chop 1/4 cup of cilantro and add it to the mixture. Add water, to cover, the vegetables and bring the mixture to a boil.
Reduce the heat to medium and simmer for 20 minutes. Cut the head of white cabbage into 1/2 and then into thirds, leaving the stem of the cabbage in. Wedge the cabbage chunks into the mixture and simmer for 10 more minutes.
Serve, making sure each bowl has chunks of all the vegetables. Garnish with a squeeze of lemon or lime. Serve with heated corn tortillas. Caldo de Res is accompanied by chopped sides of onion and cilantro which may be added according, to taste. Also, chopped jalapenos may be added for the perfect hangover cure.
The recipes for this program, which were provided by contributors and guests who may not be professional chefs, have not been tested in the Food Network's kitchens. Therefore, the Food Network cannot attest to the accuracy of any of the recipes.