Having just returned from a few days on the Island, I'll report that the situation for Vegitarians is improving. No longer relegated to just salads & sides, Almost every restaurant has at least one or two veggie options. Bangkok Cuisine on Circuit avenue offers Tofu as a protein choice with most every dish. And found it to be quite good. The Scottish bakery (on State Road in W. Tisbury) has Vegan options for both baked goods and meals (The only place on the island we could find this)
And another good meal -at Smoke n Bones (a rib joint!) Try the Fire Roasted Vegetables with Corn bread & coleslaw, Thin onion rings and Fried Dill pickles. (All fried in vegetable oil)
Unfortunately, the Vegitarian options at 2 of the finer dining (and expensive) places were very limited. L'etoile offered 2 salad choices and a vegitable plate "if available"