Heat the oil in a frying pan. Stir fry the meat for approx. 3 mins. Add the vegetables and stir fry for a further 4 mins. Pour in the water, bring to the boil, season.
Transfer the meat to the prepared baking dish. Prepare the mashed potatoes according to the packet instructions, spread on top of the meat, sprinkle the cheese over the top.
Approx. 20 mins. in the upper half of an oven preheated to 200°C.