John Tesar, in a supervisory role since January, is the latest of four chefs to put his stamp on Oak since it opened in late 2011. The spirit remains the same: the sleek elegance of kid-leather gloves. You can lunch on niçoise salad with haricots verts, a white chrysanthemum at your elbow. There were pearls among the openers. Half-moons of pasta filled with artichoke, house-made ricotta, and mint bathed in a light saffron broth. Heirloom tomatoes and compressed watermelon formed a jewel box of colors, with black-olive emulsion and rich olive oil powder as fine, modern touches. Tender lump crab and melt-in-your-mouth gnocchi were enhanced by a lemon-butter sauce, smoked trout roe, and squash blossoms in a marvelous marriage of smoke, land, and sea. Entrées lacked the same luster. Halibut with Cabernet and port reductions was dry; accompanying chanterelles crunched with grit. The fresh figs, favas, confit baby artichokes, and porcini mushrooms that accompanied free-range chicken with tasty pan juices were seasonal but less lush than they sounded. Ultimately, Oak’s creative elegance—best example: pastry chef David Collier’s orbs of compressed peach over a layered creation of mascarpone mousse, buttery biscuit, and peach gelatin humming with honey—doesn’t cease to impress.