For a richer flavor, try using ghee instead of vegetable oil. Ensure the semolina is cooled completely before adding the yogurt to prevent a lumpy batter. The consistency of the batter is key. It should be thick enough to hold its shape but not too thick that the idlis become dense. Experiment with adding other vegetables like finely chopped spinach or grated bottle gourd for added nutrition. Serve the idlis hot with sambar, coconut chutney, or your favorite South Indian accompaniments.