Dry-roast 200g of fine semolina in a pan over medium-low heat for 4-5 minutes until a warm, sandy aroma fills your kitchen. Set aside to cool completely.
Heat oil or ghee in the pan. Splutter the mustard seeds, then fry the chana dal, urad dal, and cashew halves until they turn a light, golden brown. Stir in the green chilies, ginger, and curry leaves for 30 seconds.
Pour the hot tempering over the cooled semolina. Add the grated carrots and salt to taste, mixing thoroughly to coat the grains.
Stir in 240ml of yogurt and 120ml of water to form a smooth, slightly runny batter. Let it rest for 15 minutes to allow the semolina to absorb the moisture and swell.
While resting, bring water to a rolling boil in your steamer. Grease your idli molds generously with oil or ghee.
Gently fold 1 teaspoon of Eno into the batter with a splash of water until it foams up. Spoon into the molds and steam on medium-high heat for 10-12 minutes.