A lot of curry recipes tell you to keep going until the oil separates, but for me this point never comes. I've tried putting more oil / butter in to start with, but no joy. I've also tried turning up the heat - same. Can anyone tell me where the oil comes from, and what causes it to be released?
[Edit following comment]
For example, I just made one as follows:
Coat 130g king prawns in a mixture of 1/2 tsp turmeric, 1 tsp chili powder, pinch salt and set aside
Fry half lg onion and a clove of garlic (chopped) in a generous amount of butter until onion translucent
Add 1/2 tsp cumin, 1/2 tsp coriander and stir in
Add 80g tomato paste, 1/2 cup water and leave to simmer for 5 - 10 mins
Add prawns and simmer until cooked through
When the prawns were done, the sauce was at about the right consistency but there was no sign of the oil separating out. I'd had the frying pan at a temperature where it would stop bubbling if stirred.
I left it for another few minutes but the prawns were getting overdone and so was the rice I had on the other ring, so I called time on it.