Start with the base. Heat the oil in a medium saucepan and, when hot, add the onions, stir for a couple of minutes, then turn the heat to very low.
Cook for about five minutes, until they start to soften, then add the garlic, ginger, chilli, turmeric and cumin and season.
Cook until the onions have completely softened and the spices have infused – about another 25 minutes. Check the seasoning, add half the lime juice and leave to cool, so the flavours get to know each other.
When you are ready to serve, whisk the eggs with the coconut milk and season, but only salt lightly; add more salt once the eggs are cooked, if necessary.
In a large frying pan, melt the butter on a low heat. Once it is foaming, add the onion base and stir to warm through for a couple of minutes. .
Pour in the egg mix and stir constantly to prevent the eggs from overcooking or sticking to the pan – this should take only a matter of minutes, because you want the egg mix to be quite loose
Turn off the heat, but continue to stir: the residual heat will cause the mix to carry on cooking. Check the seasoning.
Butter the toast and place a piece on each plate. Top with the egg mixture, drizzle over the rest of the lime juice and scatter the coriander and spring onions on top.