Masala Dosa Filling

My friend K helped me out with a simple recipe for the filling inside a dosa.  This looks better than the mix I used! 

Pressure cook potatoes with salt and turmeric.
Mash it but not too much.
Sauté onions with some mustard seeds (a table spoon) and a cut green chilly or two.
Mix the potatoes well with the onions and adjust salt.

I can't wait to try it now that we have a reliable source of dosa batter in the neighbourhood.