A roasted side of salmon makes a mighty impressive dish for special company, but few home cooks attempt it, largely due to the fear factor. Cooking fish can seem daunting: With most finfish like halibut, cod, or tilapia, the flesh is easily, quickly overdone. That's why we chose salmon, and a large piece at that, which offers big advantages: First, it's rich because of its oil, and is harder to overcook. Second, as with beef, individual preferences can run from rare to well done. When you cook a 3-pound piece of salmon, you can easily deliver a fish that's cooked to about medium at the thickest part and cooked through at the thinner portion for those who like it that way. Everybody, especially the cook, wins.