Preheat a cast-iron skillet (or ovenproof frying pan) with the oil, then add the onion and bell pepper (capsicum) and fry till slightly softened over medium heat, then add the chopped sausage and fry till the sausage is cooked.
Meanwhile, either steam/boil/microwave the chopped sweet potato till it is almost completely cooked (i.e. soft enough to pierce all the way through but not mushy), then add this to the pan and stir it through for a few minutes to take on the other flavours of the dish.
Preheat your broiler.
Beat together the eggs and milk in a bowl, then carefully pour it over the top of the mixture, giving it a little stir to ensure the egg is getting right between all the chunks of sausage and vegetables.
Sprinkle grated parmesan over the top, then lower the heat of the burner and leave to cook till the bottom and sides have just set, then place under the broiler to cook the top.
Once it’s finished cooking, remove and serve either warm or cold with a spicy tomato salsa or chutney and some green salad on the side.