Indian Cooking Basics: Curry Base 1: Boiled Onion Paste

Introduction:
Many Indian curries, particularly those that hail from the north of India, rely on making a base with onions (with or without other ingredients such as ginger, garlic, tomatoes, herbs and spices). There are many ways to do this – making it difficult to cover them all in one blog post – which is why I have decided to do it in a series of posts. It’s all part of the service, my friend.
Often, this base is part of the recipe depending on the specific requirements of the curry and generally speaking, the slower the onions are cooked, the better the flavour. However, this also means that you have to spend a considerable amount of time in the kitchen, which is alright if you are in a pottering-around sort of a mood, but not if you’re rushing to put dinner on the table.
Like many Indian cooks, including professional chefs, I find it useful to make the bases in bulk. Each of these different bases affects the flavour of the curry in a different way, so I often have more than one kind stashed away in the freezer at any given time. Once you have these bases handy, you can make a curry in no time at all.
A Note on the Type of Onions:
The best curries are made with onions that have lesser water content and are not too sweet, therefore ruling out Spanish & sweet onions. Red onions tend to spoil the colour of the curry and are best saved for salads and pickling. My personal favourite is the pink Rosanna onion available in the UK or the Bombay onions sold in Indian shops. However, they are either pricey or not easily available, in which case, the general-purpose brown onions work well.
Types of Onion Pastes:
The three main kinds of onion pastes are:
- Raw onion paste: This is where raw onion is ground into a paste which is then fried to obtain the curry base. I am NOT a fan of this at all as, if you are not careful, the onion oxidises quickly to become very bitter. And I also find that it lends a very strong flavour to the curry – the onion flavour asserts itself over others, which is alright if that’s the effect you are going for.
- Boiled onion paste: This doesn’t sound very glamorous, but it does the job beautifully and is my personal favourite. Here, the onion provides a subtle backdrop for the main ingredient rather than compete with it for attention. This paste works for all kinds of curries such as meat, fish, vegetables, beans but not in dals.
- Fried onion paste: Here, the onions are traditionally deep-fried before grinding them into a paste. This is also a slightly more assertive flavour which works best with meat dishes. Curries made with this base are darker in colour and often richer too. To make matters easier, fried onions are available in Indian groceries and all you have to do is to grind these up with a bit of water into a paste. However, they do have a coat of wheat flour which can marginally affect the flavour of the curry. My personal preference is to slow-roast the onions until deliciously caramelised. However, that’s another topic for another day.
Simple Or Complex Paste?
At its simplest, boiled onion paste is just chopped onions boiled in some water (not too much, otherwise you’ll spend ages reducing it when you make the curry) for a few minutes, then blending it. To make it more flavourful, spices, ginger and/or garlic may be added if you so prefer. I would not advise adding cinnamon though, as it doesn’t blend well and will give the paste a grainy texture – add it to the main curry instead.
At the other end of the scale is the kind that’s made in restaurants with a long list of ingredients including vegetables such as carrots & cabbage. The recipe that follows is my favourite – it’s generic enough so that I can build my layers of flavours in the curry without every curry tasting the same yet also not too basic.
Notes:
This yields a small quantity, for use in about 2 – 4 curries. To make it in bulk, you can easily double or triple the quantity of onions but instead of scaling other ingredients proportionately, use 1.5 or 2 x respectively.
Next time, I will show you how to use this paste to make curries.

Indian Cooking Basics: Part 1: Boiled Onion Paste
Ingredients
- 150 g onion see post for what kind
- 6 g garlic about 4 fat cloves
- 6 g ginger about 1" piece
- 6 green cardamoms
- 4 cloves
Instructions
- Place all the ingredients in a saucepan and add water to come up to about half the height of the onions. Depending on the diameter of your saucepan, this could be about ½ to ¾ cup.
- Bring to the boil, lower heat, cover with a lid and simmer for about 10 minutes.
- Turn off the heat, cool to room temperature, then blend for at least 2 minutes to get a smooth puree. You could, as I sometimes do, pass it through a sieve to ensure extra smoothness.
- Freeze in ice cube containers, then transfer to a plastic bag & keep frozen.