Cook toordal with 1 cup of water for 3 minutes in a cooker ie,3 whistle.
Add chopped potatoes and tomatoes to this and boil for 2 minute.
Add onions and green chilly to this and boil for a minute.
Next add turmeric powder and coriander leaves to this and boil for a minute.
Heat oil in a kadai add and add mustard ,when mustard splutters add fenugreek seeds,red chilly and curry leaf saute for a minute.
Next add coriander powde,asafoetida, and chilli powde to this and saute for 2 minutes.
Add this tempering to vegetable mix and boil for 2 minutes.
Add chilli powder and salt and boil for 2 minutes.
Now potato sambhar is ready to serve.