Heat the ghee in a small frying pan. Add the cumin seeds, then the mustard seeds. Let them pop.
Then add the onion, chilli and curry leaves until the edges of the onion are golden and the centres are soft.
In your tava or flat pancake pan, add a little ghee, then put in half a ladle of the dosa dough. The circumference should be about 8-10 cm's (4/5 inches) and half a centimentre thick (1/4 inch). Let the bottom cook and add the onion on top.
You will see the dough bubble like a crumpet.
Add a pinch of salt and eat it all up. Then, probably, make another one and eat that all up too. Mmmm..