I would steer clear of the burger sauce Laura unless its a low carb version (available online).
Plain mayo can be a little boring after time, why dont you try adding some spices? Ive added curry powder to mayo for coronation chicken, thats quite nice. You could try chilli powder.
Have you tried garlic mayo and lemon mayo as an alternative? or if you have the time make your own thats really nice!!!!!!!!!!
i