At first glance, this stylish izakaya and sushi bar could be another in a line of similar places that dot the San Francisco landscape were it not for a major twist: everything on the menu is vegan. Purists and die-hard carnivores may scoff, but the food is exceptional, skillfully manipulating vegetables and starches to recreate seafood-centric Japanese favorites.Spicy tuna gets a run for its money from the impressive tofuna rolls, with chili-inflected minced tofu and cucumber, crowned with creamy avocado and dusted in chili “tobiko.” A yuba salad with miso dressing and tempura-battered shiitake mushrooms stuffed with faux-crab is equally compelling. Throw in a sleek, contemporary setting, and Shizen is a winner for eaters of all stripes.