If vegetarian cooking conjures up images of tofu and paltry meat substitutions, Plenty will change those thoughts. Written by Yotam Ottolenghi, one of the UK’s most celebrated chefs, Plenty is based upon Ottolenghi’s weekly Guardian newspaper column “The New Vegetarian” and offers inspired, modern, flavorful and satisfying recipes.  While not a vegetarian (something that shocked many readers), Ottolenghi is the chef of an enormously popular restaurant in north London and is revered for his Mediterranean flavors and skillful, inventive way with ingredients.  Stir, at 102 Waltham Street in Boston, will hold three separate cookbook class sessions on August 10 – 12, beginning at 7 pm, and each participant will receive a copy of the book.  $155.  To reserve, call 617-423-STIR, or log on to www.stirboston.com.