Mix the yogurt with half the coriander leaves, the lime juice, then season and set aside.
Melt the butter in a non-stick frying pan (ideally with a base a little smaller than the tortilla) over a medium heat, add the onion and fry for 2-3 mins or until softened. Add the coriander stalks, garlic and chilli, and cook for 2 mins more or until softened but not coloured. Add the curry powder and stir to coat well. Pour the beaten eggs into the pan and, once it’s beginning to set, draw the egg in from the sides with a spatula, allowing the uncooked egg to fill the gaps at the side – this ensures the base doesn’t overcook before the top has set.
To serve, heat the tortilla in the microwave for 20 secs, then spread with the yogurt mixture. Slide the omelette on top, sprinkle with the rest of the coriander leaves and roll up, tucking in the edges if you can. Slice in half, to serve.