Brown onion paste is the caramelized onion base that sits behind almost every North Indian curry. Making it in advance collapses a 45-minute step in your curry recipe into 30 seconds of scooping from a jar — the difference between a weeknight curry that actually happens and one that doesn't.
Ingredients
- 1 kg (about 4–5 large) yellow or white onions
- 3 tbsp neutral oil (vegetable or sunflower)
- 1/4 tsp fine salt
Method
Slice the onions
Halve and thinly slice all the onions — about 1/8 inch thick. Uniform thickness matters here because uneven pieces will burn before the thicker ones are done. At 1 kg raw, you'll end up with roughly 200g of finished paste. This isn't a typo: onions are 90% water, and you're cooking almost all of it out.
Start low and slow
Heat the oil in a wide, heavy-bottomed pan (a Dutch oven or thick-bottomed sauté pan) over medium-low heat. Add all the onions and the salt. The salt draws out moisture immediately, which helps them soften without browning in the early stages. Stir to coat with oil.
Cook uncovered over medium-low heat, stirring every 5–10 minutes. Resist the urge to raise the heat — high heat browns the outside while the inside stays raw and astringent. You want the entire mass to transform slowly and evenly.
Watch the stages
- 0–20 min: Onions wilt, release liquid, turn translucent. Volume drops dramatically.
- 20–40 min: Color shifts from pale to golden. Sugars begin to concentrate. Stir more frequently now — every 3–5 minutes.
- 40–60 min: Deep golden to amber. Smells sweet and savory. Volume is now about a quarter of where you started.
- 60–90 min: Deep mahogany brown, very reduced, almost jammy. This is the target. The color should be the same shade as a dark roux — not black, not medium brown, but a rich dark amber.
If the onions start to stick or scorch in patches, add a splash of water (2 tbsp) and scrape up the fond. This is normal in the later stages and those stuck bits add flavor when deglazed.
Check doneness
The paste is ready when it smells sweet and deeply caramelized (no raw onion smell at all), the color is uniformly dark mahogany, and the mass moves as one thick, glistening layer with very little liquid remaining. A properly cooked batch has a complex, almost bittersweet sweetness with no sharpness.
Blend
Transfer the cooked onions to a blender (let them cool slightly first — hot liquids in a sealed blender can build pressure). Add 2–3 tbsp of water to help it move. Blend until completely smooth. The paste should be thick enough to hold its shape on a spoon.
Storage
- Container: Airtight glass jar or container
- Fridge: 1 week — pour a thin layer of neutral oil over the surface of the paste before sealing; the oil barrier blocks oxygen and extends shelf life by several days
- Freezer: 3 months — freeze in ice cube trays (each cube is roughly 1–2 tbsp), then pop out and store in a zip-lock bag. Pull out exactly what you need for each curry.
Notes
- How to use: 3–4 tbsp of paste replaces the onion stage of any curry base. Heat oil in your pan, add the paste, and cook it on medium-high heat for 2–3 minutes until it darkens slightly and the oil starts to separate from the edges — this is the blooming step that curry recipes call "cook the base until oil separates." Then add your tomatoes, spices, and protein.
- Cook at least 1 kg at a time — the effort-to-yield ratio is poor for smaller batches. 2 kg is even better if your pan fits it.
- Yellow or white onions work equally well. Red onions work but add a slightly sharper flavor and turn an odd gray-brown.
- Don't be tempted to use a food processor to pre-chop the onions — it releases too much liquid and they steam rather than caramelize.
- The oil-on-top trick works for any paste stored in the fridge: garlic paste, ginger paste, green chili paste. Oxygen is what causes spoilage and off-flavors.
Variations
- With ginger and garlic: Blend 1 tbsp each of fresh ginger and garlic into the finished paste for a complete "masala base." Reduces the prep even further, but the shelf life drops to 4–5 days in the fridge since ginger and garlic spoil faster.
- Fried onion garnish (birista): Before blending, reserve a few tablespoons of the cooked onions and fry them in additional oil until very crispy and dark. Cool on paper towels — they crisp as they cool. Use as a garnish for biryani, dal, or raita.
Added Sep 3, 2026 · Updated Oct 26, 2026