Bihari Mattha

Method

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   About Bihari Mattha: Mattha is the thin, spiced buttermilk that wraps up almost every Bihari summer lunch. It is drunk after the meal as a cooling digestive — the salt, spices and probiotic yogurt together help settle a heavy meal in hot weather. It takes 5 minutes and is one of the most beginner-friendly Indian recipes.

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   Use the right yogurt: Take 2 cups of plain yogurt — preferably homemade or thick Greek-style. Yogurt that is slightly tangy and 1-2 days old works better than fresh yogurt, which can be too mild. Avoid sweetened or flavoured yogurt.

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   Whisk the yogurt smooth first: Pour the yogurt into a large bowl or jug. Whisk vigorously with a wire whisk for 1 minute until completely smooth with no lumps. Whisking yogurt before adding water prevents the final drink from looking grainy or curdled.

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   Use cold water, not room-temperature: Add 4 cups of well-chilled water to the smooth yogurt. Cold water is essential — warm water can split the yogurt or accelerate fermentation, making the drink overly sour.

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   Whisk to combine: Whisk again for 30 seconds until the mixture is uniformly thin and a pale cream colour, with a light froth on top. The consistency should be like thin milk, not thick like lassi.

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   Dry-roast the cumin (skip if buying ready-roasted): If using whole cumin seeds, take 1 tsp and place in a small dry pan over medium heat. Toast for 90 seconds, shaking the pan often, until the seeds darken and smell deeply nutty. Remove from heat and let cool.

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   Grind the cumin: Once cool, grind the toasted seeds in a mortar and pestle or small spice grinder to a coarse powder. You will only need 1/2 tsp for the mattha — store the rest in an airtight jar for later use.

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   Understand black salt: Black salt (kala namak) is essential for authentic Bihari mattha. It has a distinctive sulphurous tang that ordinary salt cannot replicate. It is sold at all Indian grocery stores and is dark pink-grey in colour, despite the name.

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   Add the spices: Add 1/2 tsp of the freshly roasted cumin powder, 1/4 tsp black salt, and a small pinch of regular salt to the buttermilk mixture. Whisk to dissolve fully.

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    Taste and adjust: Dip a clean spoon and taste. The mattha should taste cooling, lightly tangy, faintly salty and gently smoky from the cumin. Adjust black salt or roasted cumin to your liking; the seasoning is the difference between flat and great.

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    Add optional aromatics: For a fancier version, add 1 tbsp very finely chopped fresh mint or 1/4 tsp finely grated ginger. Stir gently. These additions are common in summer when fresh mint is plentiful.

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    Chill thoroughly: Cover the jug and refrigerate for at least 30 minutes before serving. Mattha is a cooling drink and tastes flat at room temperature — it must be served properly cold.

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    Stir and serve: Buttermilk separates as it sits, with the watery layer rising to the top. Stir well with a long spoon just before pouring. Pour into tall glasses, garnish each with 2-3 fresh mint leaves and serve immediately. Drink slowly after a heavy meal for best digestive benefit.