Soak the tamarind in 1 cup water for 20 minutes. Squeeze it out, adding water little by little to prepare 1 cup of juice.
Choose a heavy cooking pot. Wash and clean the dal. Boil 2 cups of water and add the dal, turmeric powder and 1 teaspoon of oil. As the dal boils, skim off the foam and discard. Boil until the dal is soft and then mash it coarsely. If needed, add more water as it is boiling but do not let it get too watery. If you use a pressure cooker it will take about 5 minutes.