2 dried chipotle chiles
2 cloves
1 tablespoon cumin seeds
1 teaspoon black peppercorns
3 tablespoons vegetable oil, plus more for the baking dish
4 large garlic cloves, minced
3 medium shallots, minced
2 tablespoons minced fresh ginger
2 tablespoons jarred tamarind puree
2 tablespoons pure maple syrup
Kosher salt
One 2 1/2-pound whole fillet of skinned salmon
Flaky sea salt, for sprinkling