The texture and big flavor of the pesto makes this salmon such a pleasure to eat! And it really doesn't take much longer than preparing salmon using a marinade. The pesto ingredients get blitzed together in a food processor and pressed over the top of the salmon prior to cooking. That said, you could certainly do this in advance (up to 2 days) and cook the fish at your convenience. (Or make the pesto in advance and refrigerate until using.) My favorite way to serve this is on a spinach salad tha