Heat the olive oil in a medium non-stick frying pan with a metal handle that can go into the oven. Add the onion and fry for 5 mins, to soften. Add the shredded sprouts, sausages and potatoes and fry over a high heat to re-heat – try not to stir too much or you’ll break up the potatoes too much. Meanwhile, beat the eggs in a large bowl with plenty of salt and pepper. Heat the grill.
Pour in the egg mixture and leave to cook undisturbed over a gentle heat for 8 mins until firmly set underneath but not set on top. Put under the grill for a few mins until the top is set and just golden (if you don’t have a pan that’s suitable, then carefully slide the tortilla out of the pan onto a baking sheet instead to grill). Eat for breakfast, brunch, lunch or dinner, sliced into wedges with tomato or brown sauce, and baked beans, if you like.