That true but unfortunately you have to make an initial purchase. If you are doing a two day event buy low and replenish before the next day. If you are doing one day events then try to book them back to back or every other week to use up inventory. If you are cooking on site refrigerate or freeze unused food items. We generally tossed the rolls and open condiments but would freeze or left frozen the hot dogs and burgers. If you buy fresh then onions, lettuce and tomatoes should last at least a week. Most of the events we have done in the past it is not feasible to leave and replenish supplies. Some events are predictable enough that the same volumes work each year, others follow no pattern and what may be good this year won t work next year. Don t buy a lot of chips; we sell less than fifty bags a day. The best way to push the toppings is to offer a signature item like a Coney or New Yorker. Price your brats with the topping then leave it off if the customers doesn t want it. (A plain Whopper cost the same as one with everything.)