Slice the beef into thin, 2-inch long slices. In a medium mixing bowl, combine the beef with 1 Tbs. soy sauce, 1 Tbs. brown sugar, and 1 Tbs. arrowroot powder. Stir and refrigerate.

Meanwhile, slice one of the tangerines in half and juice it. Discard the peel. Peel the other tangerine by hand and cut the peel into large (1-2 inch) pieces. Squeeze the juice.

In a small bowl, combine the juice from both tangerines, the remaining 2 Tbs. soy sauce, 1 Tbs. brown sugar, and 1 Tbs. of arrowroot powder. Mix together until the arrowroot powder is dissolved and set aside.

In a large wok or skillet, heat the oil over high heat and add the beef. Sauté until the edges begin to crisp, about 20 minutes. Remove the beef and set aside.

Add the tangerine peel and, if needed, a small addition of oil. Sauté the tangerine peel for about 2 minutes - the peel should just begin to soften and caramelize. Add the ginger, garlic, and whole chilies and sauté until the garlic is barely golden. Add the cooked beef back to the pan and sauté an additional minute or two.

Stir in the sauce. Cook an additional few minutes, until the sauce has heated through and has thickened slightly. Serve over steamed rice with a vegetable side, such as broccoli.