⅔cupcoarsely chopped spinach, or whole baby spinach
⅔cupcoarsely chopped arugula leaves, or whole baby arugula
2tbspcoarse-ground Dijon mustard
Place salmon fillets in a shallow, nonreactive dish/pan. In a small bowl, whisk together wine, orange juice and soy sauce. Pour over salmon, cover tightly with plastic wrap and refrigerate 2 hours, turning several times.
Preheat oven to 400º. Transfer salmon to foil-lined, rimmed baking sheet, sprinkle with a little salt, and roast for 12 minutes, until just cooked through and easily flaked with a fork. Let rest, loosely tented with foil, for 5 minutes.
Meanwhile, make sauce; place spinach, arugula, mustard, sour cream, half-and-half and garlic in bowl of food processor. Process/pulse for 30 seconds or longer until greens and garlic are finely chopped and blended with other ingredients.
Plate salmon and top each serving with a dollop of mustard sauce, passing any extra sauce in a small bowl.
I use skinless salmon, but you can certainly make this with the skin on. Place the salmon skin side down when roasting. When ready to serve, the salmon will easily separate from the skin with a spatula.
The "greens" sauce can be prepared a day in advance; refrigerate and bring to room temperature before serving.