Wash the sweet potato well.Cut in squarters lengthwise with the skin still on,and chop into rolling wedges.Soak in plenty of water to eliminate bitterness.Drain,place on a heat-resistant plate,cover with plastic wrap and heat in a microwave oven for a few minutes.Wipe off any moisture.
Deep-fry the chopped sweet potato in oil at 320F slowly.When the surfaces hardren,increase the oil temperrature.
Place the water ,sugar and soy sausein a pot,and heat while stiring.When the liquidt thicken,remove from the heat.
Place the just-fried potatoes in the pot with the sauce perpared in 3.above,mix quickly and sprinkle on the black parched sesame.