How to Make It
In a mini food processor, combine the shredded coconut, onion, garlic, serrano and ginger with the 1/3 cup coconut milk and process to a paste.
In a large, deep skillet, heat the vegetable oil. Add the yellow mustard seeds and curry leaves and cook over moderately high heat until the seeds pop, about 1 minute. Add the coconut paste and cook over moderate heat, stirring, until fragrant, about 4 minutes. Add the ground fennel, coriander, cardamom, turmeric, cayenne and fenugreek and cook, stirring, until fragrant, about 2 minutes. Add the remaining 3/4 cup of coconut milk and the tamarind paste, water, tomatoes and sugar. Bring to a simmer, scraping up any bits from the skillet. Simmer over low heat for 10 minutes.
Add the cherry tomatoes to the sauce and simmer over moderate heat until just starting to soften, about 1 minute. Season the salmon with salt, add it to the skillet and simmer over moderate heat, stirring gently a few times, until just cooked through, about 3 minutes. Sprinkle the curry with the cilantro leaves and serve.
Fresh curry leaves, which resemble small bay leaves and have a savory flavor, are available from www.kalustyans.com.