Peruvian pulpo al olivo, or octopus with olive sauce, served as the inspiration for this quick but elegant dinner. The olive sauce is the standout here, and it comes together with remarkable ease. Black olives, mayonnaise and lime juice are whirred in a blender until smooth, along with a little cayenne to mimic the heat of ají amarillo, a Peruvian yellow chili paste. Cod and snapper are our first choices for this dish, but you could use salmon instead. While the fillets finish cooking with the skillet’s residual heat, we throw together a simple, colorful salad to serve on the side.