In food processor, pulse salmon, green onion, and orange zest until finely chopped. Form into 8 cakes; freeze 10 minutes. Season with 1/4 teaspoon salt. In 12″ nonstick skillet, heat 2 teaspoons olive oil on medium. Add cakes; cook 4 minutes per side.
Meanwhile, in large bowl, whisk basil, orange juice, sherry vinegar, 2 tablespoon olive oil, and 1/4 teaspoon each salt and pepper. Add quinoa and mixed greens, tossing to combine. Serve with salmon cakes and orange wedges, if desired.