When cooking for someone with multiple food allergies, there will be no one cookbook you can follow exactly. Special cookbooks eliminate one or more allergens, or avoid food groups such as meat or dairy. There's nothing on the market --- yet --- for someone avoiding bovine dairy, citrus, tomatoes, pineapple, mint, chocolate, and cola.
Luckily nowadays many of us are foodies, and options are available. Here are some of my favorite ways to substitute.
Find recipes that eliminate allergens. Start with cookbooks that avoid gluten or dairy. Find cuisines that don't rely on food you must avoid. Vegetarian or kosher cooking might have some ideas.
Look at traditional cuisines. Alsatian food, for example, uses German ingredients with French flair, and much less use of the butter, cream, and tomatoes we avoid.
Can't eat citrus? Find other tastes with zing to replace lemons, lime and oranges. Consider using ginger, nutmeg, fine vinegars, or liqueurs like kirsch as seasoning accents. Learn to love stonefruit in its seasonal variety instead of oranges.
Be an Iron Chef. We fell for this show in the Japanese version before it had subtitles, making it something from a parallel universe. The chefs must create four new dishes using the theme ingredient within one hour. When cooking for the allergic, one must be just as creative at home. Try something new! Be free to invent your own variations. Be glad you are not competing in Kitchen Stadium.
Don't attempt the impossible. Sometimes the real taste just can't be replicated. You are better off learning to enjoy new tastes than to feel frustrated or cheated by an inadequate replica. If the recipe you want relies on primary ingredients you can't have, look for another recipe.
Keep a sense of humor. We joke about recipes combining all James' allergens. Martha Stewart's pineapple-chocolate cheesecake with mint is one of the all-time winners in the "death to James" category.
Enjoy. It's food, it's nourishing, it's an adventure.