How to Make It
In a medium skillet, cook the chipotle chiles over moderate heat, turning, until they are toasted, about 4 minutes. Let cool, then break up the chipotles and discard the stems and seeds.
In a spice grinder, combine the chipotles, cloves, cumin seeds and peppercorns and grind to a powder.
In the same skillet, heat the 3 tablespoons of oil. Add the garlic, shallots and ginger and cook over moderate heat, stirring occasionally, until softened, about 5 minutes. Stir in the ground spices and cook until fragrant, about 2 minutes. Add the tamarind and maple syrup and season with a big pinch of kosher salt.
Preheat the oven to 300°. Lightly season the salmon with kosher salt. Oil a large glass or ceramic baking dish. Spread the spice paste on both sides of the salmon and set the salmon skinned side down in the dish. Fold the thin tail end under itself to make the fillet an even thickness. Let the salmon stand at room temperature for 20 minutes.
Cover the baking dish with foil and bake the salmon for about 35 minutes, until barely opaque in the center. Sprinkle with sea salt and serve.
The spice paste can be refrigerated overnight.