Add diced potato cubes to a large bowl. Soak in the water for at least 20 minutes. Soaking potatoes in water helps to remove excess starch and prevent them from browning. This step is optional.
After soaking, drain the potatoes and pat them dry using a kitchen or paper towel.
Heat oil in an iron pan on medium heat. Add mustard seeds and cumin seeds and saute till the seeds splutter.
Then add crushed garlic, curry leaves, and hing (asafoetida). Saute for a few seconds.
Add the soaked & drained potato cubes and mix them with the tempering. Cook the potatoes on medium heat, occasionally stirring until they are half cooked. It may take 7-8 minutes.
Then add spices like red chili powder, turmeric powder, coriander powder, garam masala, and salt over the potatoes. Mix well, so the spices are well coated. Continue to cook on low flame, stirring occasionally until potatoes turn crispy and golden brown.