We never expected José Andrés to advocate boiling vegetables. But in his latest book, “Vegetables Unleashed,” the Michelin-­starred chef uses a fresh approach to the old-school technique on everything from cauliflower to romaine lettuce, saying it’s the best way to season and cook vegetables quickly. Simmering vegetables in a small amount of water, fat and seasonings not only perfectly cooks the produce, it also creates a flavorful sauce as the liquid reduces.