Tadka is the name of a spice mix that has been briefly roasted in hot oil to release its flavour and fragrance. It also refers to the process of roasting spices in hot oil, known as tempering in English. Traditionally ghee is used, but extra virgin olive oil or coconut oil can be used in vegan diets. The process is very quick, perhaps as quick as thirty seconds. Heat the oil and let the spices sizzle, then add the spices and oil to the daal.