Place ginger, plum sauce and soy sauce in a small pot and warm through over low heat. Season prawns with salt and pepper, and then coat in cornstarch, shaking off excess. Dip in beaten egg, making sure it is evenly coated, and then dip in sesame seeds. In a large skillet set over medium-high heat, cook prawns in 1/8 inch of oil for about 2 minutes per side. Drain on paper towels, and then arrange on a platter with a bowl of the warm plum sauce for dipping.