5 tricks that can be used to cook with cold yogurt [should you wish to have more gravy and add some more yogurt to the achari chicken curry]: 1. Use full-fat yogurt. 2. Add it to the curry once it has reached room temperature. 3. Whisk it until it is smooth and silky. 4. Add a few tablespoons of the curry to the yogurt, before adding the whole mixture back in the saucepan. 5. Add a little gram flour [or all-purpose flour] and water to the yogurt, and mix well before adding.