Remove the eggplant stem and cut into 2cm cubes. In a medium bowl combine the soy sauce, chicken stock, chilli sauce, sugar, ground black pepper and oyster sauce. Stir together well and set aside.
In a separate small bowl combine the cornflour and water. Set aside.
Coat a large, deep frypan with cooking spray over high heat and allow a few minutes for it to get very hot.
Saute the garlic, half of the spring onions, ginger and prawns for 3 to 5 minutes stirring constantly until they begin to brown.
Stir in the mince and cook for 3 more minutes until browned; again stirring constantly.
Pour the eggplant into the frypan and stir all together. Pour the reserved soy sauce mixture over all; cover the frypan then reduce heat to medium low and let simmer for 15 minutes stirring occasionally.
Stir in the reserved cornflour mixture and let heat until thickened.
Finally, stir in the rest of the spring onions and the sesame oil.