The Flying Burrito is located a few blocks from the main part of Friday Harbor, near the airport. It is a casual restaurant with a nice variety of lunch and dinner items. Every item I've tried is good, but their OCB (Oregon Country Beef) burger and pork tacos are not to be missed.
If you are in a hurry you can also call your order in ahead of time and pick it up from their "fly through" window.
Their hours vary and are a little funky, so call ahead.