All good answers. Basically, any green and fresh veggie will go well with your fish. Asparagus, as suggested by Alix, will compliment you fish nicely. For another side, and if you think you need a starch, something like a whole-grain penne pasta, with a rich tomato sauce, complete with diced bell pepper, sliced onion, and mushrooms would go very well. Another option is to make a savory dressing, like what you serve with turkey, again with good veggies such as onion and celery mixed in. Another great side dish would be baked sweet potatoes, served with a compound butter made with butter, honey, and a touch of ginger.
The trick is to make sides with that have strong enough flavor to hold there own with the fish, but not overwhelm it. The fish should be the star of the meal, with the sides acting as strong supporting actors. The served beverage should be able to refresh the mouth, and be neutral enough to leave you ready for your next bite.
Desert, something light, like fresh strawberries, or sliced mango, or ripe cantaloupe would be a good contrast to the meal, and be healthy as well.
Seeeeeeya; Chief Longwind of the North
