"... usually because I've got tomato, peppers, coleslaw, relish or something else providing that..."
These are precisely the instances in which I would want something oily (butter, marg or mayo) as waterproofing for the bread. (Mustard also works, if it's appropriate for the sandwich.) "Everyone has the gout," as they (don't actually) say in French.
These are precisely the instances in which I would want something oily (butter, marg or mayo) as waterproofing for the bread. (Mustard also works, if it's appropriate for the sandwich.) "Everyone has the gout," as they (don't actually) say in French.