Add the butter and oil to the cast iron skillet on high heat.
When the skillet begins to smoke, add the scallops to the pan. Sear the scallops for about 1 ½ minutes on each side or until edges have a golden crust.
Transfer to a plate with mango vinaigrette. Serve immediately.
Mango Vinaigrette:
Blend all of the vinaigrette ingredients together in a food processor or blender.