Khatta dhokla: with leftover idli batter

I had idli batter leftover which was too sour for idli, so decided to try khatta dhokla with it, which is meant to be sour. This is the next best thing after Fusion Vada with leftover idli batter, which was made with 1:2 urad dal and idli rava respectively.
Ingredients:
Idli batter- 2cup ( fermented)
Oil-3 tbsp.
Yoghurt-3 tbsp
Ginger-greenchilli paste-2 tbsp
Salt
Sugar- a pinch ( I did not add but the GITS mix has a tinge of sweetness)
Eno-half tsp or soda bicarb- half tsp
Pepper-for garnishing
Tempering- 1 tbsp oil, 1tsp mustard seeds, 1/4 tsp asafoetida (optional)

Method:
1. Add oil, yoghurt, ginger-greenchilli paste and salt to the batter and mix.
2. Grease two plates with oil. Add eno or soda to the batter, give it a quick stir and pour it onto the greased plates. Sprinkle pepper powder evenly.
3. Steam it for 12-15 minutes.
4. Once ready either you can have it like that or can add tempering of mustard seeds and asafoetida, which is optional.
Serve it warm with coriander chutney or on its own