In a bowl, combine pistachios, orange zest, butter, salt and pepper until it forms a paste.
In an oven-proof skillet heat oil. Season scallops with salt and pepper and place in the skillet and sear until golden on one side. Then turn the scallops over and top the seared side with a mound of the nut paste. Place in the hot oven.
Meanwhile, prepare the vinaigrette. Squeeze juice from the orange into a small bowl and mix in oil, shallots, chervil, salt and pepper.
Remove scallops from the oven, place on a serving plate and drizzle with the vinaigrette. Garnish with chervil sprigs