British Indian Restaurant (BIR) style onion sauce is super easy to make but takes a long time so plan ahead.
This onion sauce is part of what makes do piazza curries so good. It can also be added to other curries for extra flavour.
The secret to success is in the slow cooking. I usually cook my onion sauce in a low oven over night. Doing this gives the sauce more depth. You can use the finished onion sauce exactly as it is when you take it out of the oven or blend it if you prefer smoother curries.
When you take the finished sauce out of the oven, the top will be slightly blackened. Try it. If you like the flavour, stir it in. If not, skim it off the top.
- 4 onions - finely sliced
- 2 red bell peppers - finely sliced
- Curry sauce - enough to cover plus about 200ml water
- 1 teaspoon fennel powder
- 3 whole cloves
- Slice the onions so that the are paper thin. You want to almost fill the pan you are using with the onions.
- Slice the red bell peppers and place them on top of the onions to fill the pan.
- Add the fennel powder and cloves and cover.
- Now add the base curry sauce so that it covers the onions and about 200ml water.
- Place on a low heat and bring very slowly to a simmer.
- This is when I place the onion sauce in the oven on the a very low temperature with the lid on. You can leave it there all night if you like. The longer you cook the sauce the better up to about ten hours.
- The top of the sauce will be quite blackened when you take it out of the oven. Try it. If you like it, stir it in. If not, remove the blackened bits.
- Place the finished sauce in a blender and blend until smooth or leave it chunky as it is.
- Use immediately or freeze.