Step 1Choose a large pot or Dutch oven just wide enough to hold the beef brisket. Fill it with enough water to submerge the brisket. Bring the water to a boil. Carefully lower the brisket into the pot. Boil it for about 3 minutes (this gets rid of the impurities, which rise to the surface as foam).
Step 2Using tongs, carefully transfer the brisket to a colander and rinse it in cool water. Set aside. Discard the cooking water and rinse the pot.
Step 3In the pot, combine 6 cups water, the rice wine, soy sauce, rock sugar, ginger slices, star anise, cinnamon stick and dried tangerine peel. Bundle up the cumin and fennel seeds in a piece of cheesecloth and tie it shut with a piece of string. Add to the pot.
Step 4Cover the pot and bring the mixture to a boil. Lower the heat and carefully place the brisket in the liquid. If necessary, add more water to ensure that the brisket is covered. Return to a boil, then simmer for about 2 hours, until fork-tender.
Step 5Remove from the heat, uncover and allow to cool. Remove the spices, then refrigerate the brisket overnight to allow the flavors to meld. (If serving immediately, proceed to the next step.)
Step 6Transfer the brisket to a cutting board and cut into one-third-inch slices. If the brisket was cooled or refrigerated, place the pieces in a large saucepan and ladle in just enough of the braising liquid to cover. Warm over medium heat until heated through.
Step 7Remove the meat with a slotted spoon or tongs, and arrange the pieces on a serving platter. Pour a little of the liquid over the beef. If you want a thicker sauce, cover the beef with foil to keep warm. In a cup, combine the cornstarch with 2 tablespoons water. Bring 1 cup of the braising liquid to a boil and add the cornstarch mixture, cooking and stirring until thickened, about 1 minute. Pour the sauce over the beef. Garnish with sliced green onions, if desired, and serve with red chile sauce.
Step 8Save the remaining braising liquid. Strain into an airtight container and refrigerate for up to 3 days, or freeze. Discard any congealed fat on the surface. The next time you make brisket, use this liquid in place of some of the 6 cups of water. Add more water to cover the meat and toss in a new batch of rice wine, soy sauce and spices.