The best onions for Indian food are brown onions, or yellow onions. They have a strong and robust flavour. White inside, they deliver a rich onion taste when cooked. If you sauté sliced onions without oil, the moisture content in the onions will reduced faster. You can then add just a little oil to sauté the onions. This way, you tend to use less oil, and the sautéing takes less time.