First grind the oats in a mixer grinder.Chop the onion, tomato, green chillies and coriander leaves. Whisk the curd well.
Add grinded oats, rice flour, asafoetida, curd and salt in it. Mix it and then add water and make a batter similar to a dosa consistency batter. Add baking soda to it, mix it and keep it aside.
Heat 1 tbsp of oil in a tawa on medium flame, pour a ladle of batter and spread a little bit.
Sprinkle little sambhar masala on it.Top it with chopped veggies and gently press them.
Cook until the base is done well and then flip it and cook it well from other side and then serve it hot.