1 large clove garlic
1 tsp. garam masala
1 tsp. cumin seed, toasted and ground
1 tsp. coriander seed, toasted and ground
1/4 tsp. cayenne
4 to 6 cups extra-virgin olive oil
Four 3/4- to 1-inch-thick skinless center-cut salmon fillets (6 to 7 oz. each)
4 lemon or lime wedges
Peel and smash the garlic clove and a pinch of salt to a paste, either with a mortar and pestle or by mincing and then mashing it with the side of a chef’s knife. Combine the garlic, garam masala, cumin, coriander, cayenne, and 1 tsp. salt in a small bowl. Add just enough of the oil to turn the spice mixture into a smooth paste, 1 to 2 tsp. Rub the spice paste all over the salmon and let it sit at room temperature for about an hour.
Position a rack in the center of the oven and heat the oven to 225°F.
Measure the thickness of the fillets and pour the same depth of oil into a 10-inch straight-sided sauté pan. Heat over low heat until the oil reaches 120°F, 2 to 3 minutes. Put the salmon fillets in the oil in a single layer and immediately transfer the pan to the oven. Poach until a few small whitish droplets rise to the surface of the fillet, 25 minutes. Transfer the salmon to a wire rack to drain for a few minutes. Serve warm with lemon or lime wedges.