Simmer until you get the specified gravy regularity (which happens to be neither thin nor very thick but medium or slightly thick consistency). Then include garam masala powder and dry mango powder. If you don't have dry mango powder, then insert ½ to 1 teaspoon lemon juice. The BBC https://www.youtube.com/watch?v=YXBT6Xp4jbo&feature=youtu.be