After five years away, chef Kate McLean has returned to this venerable bastion of upscale dining, and her update of the 57-year-old restaurant’s menu is worthy of applause. Witness a plate of perfectly cooked spaghetti alla chitarra (so named for the pasta cutter, which has guitar-like strings) graced with a slightly sweet Meyer lemon sauce and scattered with crispy squash blossoms for texture and balance. Equally fine is the dish called Rib- bons and Squares, pristine raw ahi tuna with touches of avocado in a soy-lime vinaigrette. Our red meat aficionado praised his hunk of Prime filet mignon, cooked to perfection, with black truffle butter and a side of silken potatoes. We loved our side order of pommes soufflés, which we can only describe as large wedges of air, each surrounded by a golden crust. Less successful was a snow-white slab of red snapper, overcooked to dryness and almost, but not quite, saved by lumps of crab and an intensely rich Barolo reduction. Nevertheless, we enjoyed the attentive, professional service and a gracious setting with soaring ceilings, arresting artwork, and actual white table- cloths. We also appreciated an improvement to the extensive wine list: 75 bottles for $75 or less. As for dessert, the soufflés are rightly famous, so ask about them when you order. They often sell out.