In a mixing bowl, add handvo flour, yogurt, red chili powder, turmeric powder, asafoetida, chopped curry leaves, ginger-green chili paste, salt and oil. Add 1 cup water.
Mix them well.
Add cumin seeds. Mix well. You can add cumin seed in the first step. I forgot to add it and so added later.
Add the chopped spinach and remaining water. Mix well. The batter should not be runny.It should be thick like a cake batter. At this stage you can cover the batter and keep for 5-6 hours for fermentation and then make vadas. I kept it aside for 30 minutes.
Since I did not keep batter for fermentation, I added eno (fruit salt) before making vadas. Take half batter in a bowl and add 1/4 tsp of eno. Mix it lightly . The batter is ready to use. Once this batter is finished, make the other batter with by adding eno. The effect of eno if added to the entire batter would become less with time and then we end up getting dense vadas.
Heat and brush the paniyaram pan with the oil. (you can deep fry the vadas in oil at this stage).
Pour batter in the indents of the pan.
Cover and cook on medium heat for 6-7 minutes.
Remove the lid. The bottom side will be cooked and the upper side of the vada will be dried.
Now flip the vadas on another side to cook with a toothpick or wooden skewer. If you crispy vada add little oil to cook on another side.
The hot less oil handvo flour spinach vada are ready to serve. Serve them hot with ketchup or chutney.