Stopped off for vegetable sushi on the way to the wedding just in case. In doing this it takes the edge off in case there is nothing available. They had beef , chicken and fish. All the vegetables were sauteed with oil .

Note: many catered affairs have most of the menu prepared ahead of time, as do many restaurants.

I asked a server if they had any vegan offering with out oil. They steamed this large plate and found me amount 200+ guests.  In conclusion , most people will be happy to accommodate you if they can.