Preheat oven to 400°
To prepare sauce, spoon yogurt onto several layers of heavy-duty paper towels; spread to 1/2-inch thickness. Cover with additional paper towels; let stand 5 minutes. Scrape into a bowl using a rubber spatula. Add sour cream and next 8 ingredients (sour cream through 1/4 teaspoon salt). Cover and chill.
To prepare salmon, place fennel, coriander, and cumin in a spice or coffee grinder; process until finely ground. Combine spice mixture, breadcrumbs, 2 1/2 teaspoons salt, and black pepper in a shallow dish. Dredge skinned side of salmon in spice mixture. Heat a large nonstick skillet coated with cooking spray over medium-high heat. Add half of salmon, crust side down; cook 3 minutes or until golden brown. Transfer salmon, crust side up, to a baking sheet lined with aluminum foil. Repeat procedure with remaining salmon. Bake at 400° for 8 minutes or until fish flakes easily when tested with a fork. Serve with sauce. Garnish with cilantro sprigs, if desired.