Undoubtedly the best topping, to any great curry dish. The sweetness of the onions works so well with this spicy dish. You could buy them already fried, from the supermarket, but the home made ones are miles ahead in taste and flavor. I usually use red onions as they are sweeter and have less water, therefore they are crispier when cooked.
Slice them thinly using a mandoline (if you have one) and fry them in plenty of sunflower oil (or any other frying oil of your choice), over medium heat, stirring occasionally. Don’t crowd them in the frying pan, it’s best if you do it in batches. Careful not to burn them, as overcooked onions taste bitter. What you are looking for is a nice golden colour.
When you take them out of the pan, leave them to drain on kitchen paper. The onions will not be really crispy when you take them out of the pan, but they will become crisp after they cool and the paper absorbs the excess oil.
You can keep them sealed in a plastic container for 3 days.