Perhaps it's just a localised thing, but does anyone else normally phrase it as "bread and soup" instead of the other way around? It just sounds a little... weird that way (more in the 'unnatural' sense than in the 'absurd' one)...
I typically put either the more appetizing one or the one of greater quantity first, so for me it could depend upon either the particular soup and the particular bread, or how much of each is there.
Soup is a main meal with bread as a side dish. So it makes sense to list soup first.
Well personally i always say "joy and waffles, please." Any other way just seems unnatural