Nigella Lawson prepares good food quickly. This time she shares clever ideas for workday entertaining. For a casual supper she makes crab and avocado salad with a zesty Japanese dressing. A sit-down two course dinner calls for one-pot classic coq au Riesling followed by juicy jumbleberry crumble. Plus there's a three course crowd-pleaser of quick crostini with avocado and green pea hummus, followed by steak with lemon and thyme, with Eton mess for pudding.