Keep it fresh
If you’re invited to join family and/or friends for a Christmas at their place then offer to bring a salad or a vegetable mix that you know you would enjoy and work for you. Get creative with the flavours and bulk it up with all your favourite ingredients. This way if this salad or vegetable side is the only thing on the table to suit your tolerance levels then you can be sure there is a tasty meal there for you. Also I’m sure your host wouldn’t mind the extra help.