My Favorite fish Salmon is one of the richest, strongest flavored fish available, it combines well with piquant sauces. This one is made with tomatoes and chipotle chiles. You can find these chipotles canned in dark red adobo sauce.
To prepare the sauce: In a medium saucepan, warm the olive oil over medium-high heat. Add the onions and cook until soft, 4 to 5 minutes, stirring occasionally. Add the garlic and oregano, and cook until the garlic is light brown, about 1 minute, stirring occasionally. Add the tomatoes (including the juice) and the chile. Season with the sugar, salt, and pepper. Bring the sauce to a boil, then lower heat to a simmer. Cook for 30 to 40 minutes, stirring occasionally and crushing the tomatoes with the back of a large spoon as they soften. Carefully pour the sauce into a food processor. Puree and return to the pan. Keep warm over low heat.
Generously brush or spray the salmon fillets with olive oil; season with salt and pepper to taste. Grill the fillets, flesh side down, over Direct Medium heat until you can lift them off the grate with tongs without sticking, 7 to 8 minutes. Turn the fillets and finish cooking them, skin side down, for 2 to 3 minutes. Slip a spatula between the skin and flesh, and transfer the fillets to serving plates. Serve warm with the sauce.