Combine first 5 ingredients in a small saucepan; bring to a boil. Reduce heat, and simmer 3 minutes or until slightly thick.

Heat a cast-iron skillet over medium-high heat. Combine 2 tablespoons tangerine juice, chile powder, red pepper, and salt in a large bowl; add scallops, tossing gently to coat. Add scallops to pan; cook 2 minutes on each side or until browned. Remove from pan; keep warm. Add wine to pan, scraping pan to loosen browned bits; bring to a boil. Add kumquat mixture and butter. Reduce heat to low; stir until butter melts. Arrange 5 scallops on each of 8 plates; top each serving with 3 tablespoons sauce; sprinkle with 1 teaspoon nuts.