Grease an 8-inch cake pan with oil. Bring 2 inches of water to a boil in your steamer over medium-high heat. Ensure the lid is tight to capture the steam.
Sift the besan and semolina into a large mixing bowl to remove all lumps and incorporate air.
In another bowl, dissolve sugar, salt, lemon juice, oil, ginger-chili paste, and turmeric in 200ml of water. Pour into the flour and whisk in one direction until smooth. Rest for 10 minutes.
Add Eno fruit salt to the batter with a teaspoon of water on top. Whisk gently in one direction for 10-15 seconds until the batter doubles in volume and becomes pale and frothy.
Pour the batter immediately into the greased pan and steam on high heat for 15 minutes without opening the lid.
Test with a toothpick in the center; it should come out clean. Let the dhokla cool for 10 minutes, demold, and cut into squares.
Heat 1 tbsp of oil. Sizzle mustard seeds, sesame seeds, green chilies, and curry leaves. Add 120ml water, sugar, and lemon juice. Boil for 1 minute.
Spoon the warm tempering liquid evenly over the warm sliced dhokla. Garnish with chopped coriander and fresh grated coconut.