What the law requires
The EU Food Information Regulation (LMIV, Regulation (EU) 1169/2011) requires declaration of 14 allergen groups: cereals containing gluten, crustaceans, eggs, fish, peanuts, soybeans, milk including lactose, tree nuts, celery, mustard, sesame, sulphur dioxide and sulphites, lupin and molluscs.
For loose goods — and a buffet is loose goods — the German implementation also permits verbal information. But that is only allowed if written or electronic documentation exists and is accessible on request, and if a clear notice pointing to it stands at the buffet.
What a caterer can genuinely adapt
This is where bought-in components differ from freshly cooked food. Anyone reheating pre-produced goods can usually only remove a dish when there is an intolerance. Anyone cooking on the day can prepare the dish differently instead.
A concrete example from our first catering job: the host asked which dishes contained milk. Rather than removing half the buffet, we converted the menu to lactose-free — korma with coconut milk instead of cream, curries without butter or yoghurt, rice without ghee. Only the naan stayed as it was, at her explicit request. At no extra charge, and barely a difference in taste.
The questions worth asking
Do you cook fresh on the day or reheat pre-produced food? Can you adapt a dish or only omit it? Does the adaptation cost extra? Do I get the allergen list in writing before contract? How do you label at the buffet itself?
That last question is rarely asked and the most practical: your guests stand at the buffet, not you. Small cards on the trays save twenty individual conversations.
And the honest part
A kitchen that also works with nuts, wheat and milk can never fully exclude traces. Anyone promising absolute freedom from traces without knowing the production is not telling you the truth. With severe allergies this belongs in an open conversation, with the person affected, before booking.