Boil and peel potatoes. I have used baby potatoes, you can use big potatoes and halve them.
Puree ginger, green chillies and tomatoes.
In a kadhai, add mustard oil, heat it till it's smoking point. Switch off the gas and let it cool a for 1-2 minutes.
Add panch phoron spice mix and hing, when the seeds crackle, add tomato puree.
Cook tomato puree for 2-3 minutes, then add cumin powder, coriander powder, garam masala and sugar. Cook for few minutes till the masala leaves oil.
Add potatoes and mix well. Masala should coat the potatoes. well. Add 1/2 -1 cup water.
Cover and cook for 5-10 minutes. Keep the consistency of curry as per your liking. I made it on the drier side as we I also had made Chole Masala along with it.
Garnish with finely chopped fresh coriander leaves. Serve hot with Luchis or Pooris. the se go well with rotis or paranthas also.