- ¼ cup lemon juice (from about 1 lemon), or ¼ cup lime juice (from about 2 limes)
- ½ teaspoon Sambhaar or curry powder
- 2 teaspoons kosher salt
- 1 teaspoon ground peppercorns
- 6 salmon fillets (6 ounces each), any small bones removed with tweezers
- 2 tablespoons canola oil
- 30 curry leaves, roughly torn
- 1 to 6 dried red chiles (optional)
- 1 tablespoon plus 1 teaspoon mustard seeds
- 2 teaspoons cumin seeds
- 1 teaspoon ground peppercorns
- 2 medium red onions, finely chopped
- 2 tablespoons plus 2 teaspoons kosher salt
- 6 medium tomatoes, finely chopped
- 2 cups coconut milk
- 2 tablespoons canola oil
- ½ cup chopped fresh cilantro
- Place the marinade ingredients in a gallon-sized resealable plastic bag. Add the salmon and turn to coat. Refrigerate for 30 minutes, or up to overnight (note that salmon marinated overnight will cook faster).
- Preheat the oven to 400°F. To make the sauce, heat the canola oil with the curry leaves, chiles (if using), mustard seeds, cumin seeds, and ground peppercorns in a large skillet over medium-high heat for 2 minutes or until the mustard seeds begin to pop. Add the onions and salt and cook, stirring often, until the onions are soft and just beginning to brown, 5 to 8 minutes. Add the tomatoes and cook, stirring occasionally, until they break down and the sauce thickens, about 10 minutes. Stir in the coconut milk and bring to a simmer. Transfer to a large baking dish.
- Heat the canola oil in a large skillet over high heat until it shimmers and is hot, 2½ minutes. Add 3 to 4 salmon fillets, skin side down, and sear until browned, 2 to 3 minutes. Place the salmon skin side on top of the sauce in the baking dish, taking care not to overlap the fillets. Repeat with the remaining salmon fillets. Bake the salmon until it is opaque at its edges and nearly cooked through to the center, 12 to 15 minutes (if the fillets are thin, reduce baking time to 10 to 12 minutes). Remove the salmon from the oven, sprinkle with cilantro, and serve skin side down with plenty of sauce.