It’s a great time to be a vegetarian, as world-class chefs turn their attention to vegetables, moving them from side dish to star of the show. Gone are the days of making do with a sad, boring salad for dinner. Bring on “whole vegetable” cooking, where every inch of the product, from root to leaves, is used. Esker Grove, the new restaurant in the Walker Art Center, doesn’t bill itself as vegetarian, but chef Doug Flicker is serving up some stellar vegetable-centric dishes. Flicker, who delighted diners during the six-year run of the now-shuttered Piccolo, has taken his considerable talents to the stylish new space that overlooks the Walker’s sculpture garden. Dishes like cauliflower with preserved mushrooms, onion, and puffed wild rice, or red rice with miso, kale, preserved mushrooms, and rotisserie vegetables mean even carnivores won’t miss the meat. And if you do want a salad, the Esker Grove version with seaweeds, herbs, and vegetables is a revelation.