"Idiosyncratic" means something like "eccentric". It is not exactly the same, since "eccentric" has the connotation of weirdness, whereas "idiosyncratic" just means unique to that individual. Of course, it is a matter of opinion whether someone's unique habit or way of doing things is weird.
Saying that forksandspoons uses cutlery in an idiosyncratic way means that a fork is usually used with a knife, and a spoon is usually used alone. It is not common practice to use a fork and a spoon together. Therefore doing so is idiosyncratic.