Dry roast semolina (rava) on medium heat until it turns aromatic; cool completely.
Mix roasted rava with yogurt, water, and salt; let it rest for 15 minutes.
Heat oil; add mustard seeds, curry leaves, green chilies, and cashews. Add to batter.
Enhance the batter by mixing in grated carrots or finely chopped coriander leaves.
Just before steaming, add baking soda or eno for a fluffy texture.
Pour batter into greased idli molds; steam for 10-12 minutes until cooked.
Serve warm with coconut chutney and sambar for an authentic South Indian experience.