Quick: If you could have one food to eat while marooned on a desert island, what would it be? How about miso soup? It's life-sustaining, clean, genuine, and wholesome, and the murky bean-paste broth and floating bits of briny seaweed, scallion, and soft tofu cubes are fun to eat sans utensil (handy on a desert island). Sushi Ya is our favorite purveyor of this elixir of life. Located in a dull Owings Mills shopping center, the restaurant is light and airy, with blond wooden chairs, clean white walls, and a few spare and stylish Japanese prints. Like the soup, the house sushi is similarly unalloyed. Snowy white rice, herbaceous nori, dabs of antiseptic wasabi, and the brilliant flavor of recently living marine creatures are melded in carefully rolled or shaped offerings. If miso soup and sushi leave you feeling too virtuous, the vegetable tempura is a delicious way to reintroduce saturated fat into your system.