Methods

1. Rinse the salt cod under cold water to remove any excess salt. If it’s one big fillet, cut it into a few smaller pieces. Place the rinsed cod in a bowl, cover with cold water, and refrigerate for 12 to 24 hours, changing the water every few hours. 
2. Pat the desalted cod dry and cut into ¼” cubes. Place in a bowl and toss with ½ teaspoon ground turmeric. Set aside.
3. Heat the coconut oil in a large skillet over medium heat. When the oil is shimmering, add the curry leaves—be careful, these will crackle and pop!—and cook until bright green and translucent, 10 to 30 seconds. Add the onion and cook, stirring frequently until softened and turning golden brown around the edges, 7 to 10 minutes. 
4. Reduce the heat to medium, add the seasoned cod and the Guntur Sannam chili powder, and cook until the cod is cooked through and flakes when pressed with the back of a fork, 5 to 7 minutes. Turn the heat off and stir in the juice of ½ lemon. Taste and season with more lemon juice, if you like a little more acidity.