Heat most of the oil in a pan. Fry the onion for 10 mins until starting to caramelise, then add the potato and fry for a further 8 mins until the edges are beginning to crisp.
Add the curry powder, some seasoning and a splash of water. Cook for 1-2 mins, then scoop the mixture onto a plate. Wipe out the pan with kitchen paper.
Increase the heat and add the remaining oil to the pan. Add the eggs and some seasoning, then use a spatula to stir a few times. Leave to cook for 30 seconds.
Pile the potato filling onto one side of the omelette while the top is still a little soft. Fold the omelette over to cover the filling and cook for a final 1-2 mins, if you like your omelette set all the way through.
(Alternatively make the omelette in the oven, then serve on dish with potato mix on top).
To serve, top with a dollop of yogurt and drizzle some chilli sauce