White asparagus has a very short growing season, and is typically seasonably available in May or June.  You may possibly be able to purchase a Peruvian variety of it at other times of year.  What makes it white? It is grown with the dirt mounted around the stalk, depriving it of light.  Because of this lack of sunlight, it is unable to produce chlorophyll to make it green. Lacking bitterness and milder in flavor than its sun exposed green sister, white asparagus does need to be peeled, as the outside is quite tough. What lies beneath is tender and heavenly.

Austrian Chef Kurt Gutenbrunner is chef/co-owner of the NYC treo of restaurants Wallsé, Café Sabarsky, and Blaue Gans.  In this video he shares his recipe for a simple white asparagus with vinaigrette.

Recipe courtesy of Kurt Gutenbrunner and New York Magazine:

3 pounds, about 16 pieces white asparagus
1 ½ tablespoons salt
1 tablespoon sugar
2 ounces butter
1 small piece of baguette or white bread

Drape a dish towel over a large, inverted mixing bowl. (1) To peel asparagus, grip the spear with three fingers, protecting the tip, and lean it against the bowl to prevent it from breaking. With a swivel vegetable peeler, remove the thick outer layer starting just below the tip, turning the spear as you peel. Peel them well, as the skin can be tough and bitter. (2) Trim approximately one inch off the woody end of each spear. Add the salt, sugar, and butter to 4 quarts of water in a large pot and bring to a boil. (3) Add the bread, which helps eliminate bitterness, and the asparagus, and cook for about 8 minutes, until cooked through but still firm. Remove asparagus and dry on a towel. Serve at room temperature with an herb vinaigrette (made with good extra-virgin olive oil and lemon juice) or hollandaise sauce.