Soak the imli in the warm water for about 1/2 hour. Using your fingers or the back of a spoon, squeeze as much of the pulp as possible out into the water. Pour the imli water along with the chili powder into a saucepan and bring to a boil. Turn the heat down to medium low and cook (about 40 minutes), stirring occasionally till the sauce thickens and measures 1/4 cup.