Pic: Goran Kosanovic

The sauce can be refrigerated for up to 3 days, or frozen for up to 1 month.

4.5 servings cups

Ingredients

2 medium yellow onions, diced (2 cups)

3 cups water

1 cup unsalted, chopped cashews

1 cup whole-milk plain yogurt

2 tablespoons canola oil

2 tablespoons homemade or store-bought ginger-garlic paste (see NOTE)

Method

Combine the onions and water in medium saucepan over medium-high heat. 

Bring to a boil, then cover and cook for about 10 minutes, until the onions have softened.

Transfer the onions and their cooking water to a blender. 

Remove the center knob of the lid so steam can escape. 

Add the cashews and puree until smooth for at least 1 minute, starting on a low speed and gradually increasing to high.

Pour into a bowl, then stir in the yogurt.

Heat the oil in a large saucepan over medium heat. 

Once the oil shimmers, stir in the ginger-garlic paste and cook for 30 seconds, stirring constantly, then stir in the yogurt mixture. 

Cook for about 20 minutes, stirring often; about halfway through, the mixture will begin to sputter so keep an eye on it, and keep stirring to avoid scorching, to form a thickened sauce.

The korma sauce is ready to use, or cool completely before storing.

Note

To make about 2 cups of ginger-garlic paste, combine 1/2 cup chopped (unpeeled) fresh ginger root, 8 ounces (1 1/2 cups) garlic cloves and 3/4 cup water in a blender; puree on HIGH until smooth. Transfer to an airtight container; seal and refrigerate for up to 1 week, or freeze for up to 3 months.

Adapted from "Rasika: Flavors of India," by Ashok Bajaj and Vikram Sunderam, with David Hagedorn.