In a large bowl, place the cooked rice.
Pour 4 cups of water over the rice, ensuring that the rice is fully submerged.
Cover the bowl and let it sit overnight at room temperature. The rice will ferment slightly and develop a sour taste.
Rinse the fish pieces and pat them dry.
Rub the fish with ground turmeric, red chili powder, and salt. Let it marinate for about 10-15 minutes.
In a large pan, heat the mustard oil over medium heat until it starts to smoke slightly.
Carefully add the marinated fish pieces to the pan.
Fry the fish for about 3-4 minutes on each side, or until they are golden brown and crispy. Remove from the pan and place on a paper towel-lined plate to drain any excess oil.
Drain the fermented rice (Panta Bhat) and place it in serving bowls.
Enjoy your meal!