Roasted Halibut with Tomato-Caper Relish

When I have a group over for dinner and I don’t have much time to cook but I still want to make something that looks impressive, I cook a large piece of fish and serve it family style. On a big platter, it looks much more dramatic than individual pieces of fish. Everyone takes as much or as little as they want. I made this halibut a couple of summers ago for my friend Mark’s birthday party; it was an instant hit and has become a regular on my party menus. I usually buy the fish with the ski