I wouldn't expect a commercial airline to cook or serve (whether they would allow the use of their silverware it questionable but usually there aren't any extra plates, etc. on board) outside food unless it was somehow ordered through the airline. [I'm thinking of the AF system where coach and premium economy passengers can order and prepay for special gourmet meals in advance, IIRC duck breast or Italian. I'm not sure whether they come from AF's normal catering supplier.] If the food is ready to eat and doesn't require refrigeration, you could certainly open the package and eat it in a self sufficient way, with or without beverages supplied by the airline (but on almost all airlines, you cannot consume your own alcohol on board).