First of all for making idada put idli batter in a bowl then add in salt, eno and mix it well, now put this batter in a greased plate and make a thin layer on plate so idada will be soft and thin.
Now put the plate in steamer, make sure that before putting the plate there should be steam in steamer then only put the plate, now cook it with lead for 10-12 minutes.
After 10-12 minutes take out the plate from steamer and let it cook for few minutes, when idada becomes cool remove it from plate and cut into diamond shape, so idada is ready.
Now for making Usal heat oil in a non stick pan then add in cumin seeds and wait till it start slathering, now add in onions and cook till it becomes light golden brown.
Now add in ginger garlic chilli paste and saute well for little time then add in tomatoes and cook till become soft.
Now add in salt, turmeric powder, coriander powder, red chilli powder, garam masala and cook all the spices for little time then add water as per required.
Now add in cooked green peas and lower the heat to medium and cook it for 5-6 minutes, after 5-6 minutes turn the heat off and add in lemon juice and mix well, Usal is ready.
Now first put idada in a serving bowl the put some Usal on it, now again put idada then some Usal on it, now put some besan sev and chivda on it, now again put idada on it and garnish with some onion and lemon slices and serve.