Anne Byrn, the eminent Cake Mix Doctor, showed us that a dash of creativity, a few additional ingredients and a generous helping of her inspired ideas could turn ho-hum, store-bought cake mixes into superb confections. So, assuming she did not live by cake alone, her pleased patients began to ask what the Doctor whipped up for the rest of the meal. The answer is found in The Dinner Doctor, Byrn's practical prescriptions for serving busy, hungry families food that tastes fantastic but is simple to assemble. The basic technique is, no surprise, doctoring expanding on the cornucopia of convenience foods available in our ever-improving supermarkets. The trick is to choose the main ingredient wisely, doctor it intelligently and use quick, classic techniques to bring out the flavor. And there's lots of flavor in the more than 230 recipes Byrn supplies: just try the White Bean Soupe Au Pistou, Garlicky Cheese Grits Casserole, Shrimp Curry in a Hurry or Mexican Lasagna. Every recipe is topped off with a tip, and over a dozen lists of "15 Ways to . . . " offer extra-quick fixes for everything from a deli roast chicken to a can of baked beans, a bottle of salsa or box of brownie mix. This is medicine that's easy to take!