Remove salmon fillets from refrigerator and allow to rest at room temperature 10 minutes. Meanwhile prepare sauce.

For the sauce, add sour cream, green onions, cilantro, lime juice, garlic and season with salt to taste (about 1/4 tsp). Process until cilantro has been very finely minced. Set aside at room temperature while preparing salmon.

In a small bowl whisk together cumin, coriander, cayenne pepper, 1/2 - 3/4 tsp salt (depending on how salty you like things) and 1/2 tsp black pepper. Dab both sides of salmon dry with paper towels, season both sides evenly with cumin mixture and lightly rub over salmon. Heat a (heavy) 12-inch non-stick skillet over medium-high heat. Add oil and once oil is shimmering add salmon (top side down first. Also leave space between fillets) and cook about 4 minutes, without moving, on the first side un