All wild salmon--and now some farmed--is considered a sustainable choice. For farmed, ask for fish that's raised in land- or tank-based systems. For more information about sustainable seafood, go to seafoodwatch.org.
Salmon is easy to prepare and make absolutely gorgeous once you know how to cook it properly. The fillets cook fast and continue to cook when off the heat. For the best texture, cook about 3 minutes per 1/2 inch of thickness. Check the doneness with an instant-read thermometer (it should be about 130°F) or peek into the thickest part of the flesh with a fork--it should be just opaque.
1/2 vegetable, 4 lean meat, 1 1/2 fat