If a die-hard vegan has no choice but to go to that particular restaurant (for instance if it's an outing planned by someone else, such as a business dinner, and they're required to go), then find some things on the menu that are vegan - a plain baked potato, and a green salad with oil and vinegar should certainly fit the definition of vegan. In all likelihood, the bread will probably also be vegan - eat up.

It's ONE meal, you won't starve to death if you don't have an elaborate main dish made from tofu and wheat grass on the menu.