In a mixing bowl, whisk together the egg white, sesame oil, five spice powder, and cornstarch; season with salt and pepper. Add the beef, toss to coat in the marinade, and stick it in the refrigerator for 30 minutes. In the meantime…
Pour the peanut oil into a wok and place over high heat. Heat the oil to 350┬░F.; this will take about 15 minutes. Toss the tangerine slices with 1 tablespoon of the cornstarch. When the oil is smoking hot, quickly fry the tangerine slices for about 4 minutes. Frying the tangerine first removes the bitterness from the skin and the slices become crispy so you can eat them whole. Carefully remove the tangerine slices with a strainer to drain on a paper-towel-lined platter; their shape should remain intact.
Bring the oil back up to the smoking point and add half of the beef. (If you fry all the meat at once the oil temperature will drop and the beef will stew instead of crisp.) Fry for 2 minutes and then remove to a paper towel to drain; repeat with the remaining beef. Very carefully drain all but 1/4 cup of the hot oil into a heat-proof container. Stir-fry the ginger, garlic, green onions, and chiles in the remaining oil until they perfume. Add the green beans; season with salt and pepper. Mix the chicken stock with the remaining tablespoon of cornstarch and add it to the wok. Add the soy sauce, vinegar, and sugar. Simmer until the sauce is thick and the beans are tender, about 10 minutes. Return the beef and tangerines to the pan and coat. Scatter the sesame seeds on top. Serve with steamed rice.
Edited: October 14th, 2009