Kitchen quality can be difficult to maintain, but operations are an important part of your business strategy. Some big restaurant chains employ an individual whose only job function is quality control. Your chefs are the ones ordering the food, but make sure that they are selecting quality ingredients from reliable sources. Cutting corners can shave pennies at a time off of your food costs - which adds up in the long term for sure - but as a strategy, your food quality will suffer and so will your reputation - and your future business. Certain products are ripe for abuse by shady suppliers, and being aware of these potentially weak links in your supply chain will allow you to let you Chef know what questions to ask the suppliers - if they are not aware. Up your food quality by shopping locally and keeping things artisanal whenever possible, and be wary of the following ingredients:
Olive Oil: rancid oil sounds pretty gross right? Well, a surprising amount of olive oil is rancid and defective. The US is unfortunately known as ripe territory for less than reputable dealers looking to unload product which would not pass muster, in, say, Italy. Make sure to taste and test your oils, particularly those used for dressings, to avoid any unsavory flavors in your dishes.
Honey: if it's not produced (and marked) as a local product, there's a very good chance that the honey your purchase is cut with high fructose corn syrup or other fillers which are very much not healthy (or organic). To ensure quality, buy from a local source and mark it as local on your menu. Your customers will appreciate the quality and you can pass on any additional cost in the menu.
Steak and hamburger: have you heard of meat glue? Pink slime? Look them up if you have a strong stomach. Cheap beef is often low quality beef, and no amount of clever seasoning or expert preparation will hide the bland and sometimes chemical taste of the fillers added to sub par products. Hope for high quality steak cuts and grind hamburgers in house in order to ensure that your customers have a meat dish they will want to order over and over again.