There are an estimated 20 million American adults who are vegetarians, and this fact creates an excellent opportunity for the budding restaurateur who'd like to start a vegetarian restaurant. Like any restaurant business, conducting a market survey in the area where the restaurant will be established can help indicate consumer demand. Many vegetarian restaurants also sell food products as well as vegetarian cookbooks, and this can be a terrific way to increase profits. Furthermore, also seek opportunities for a lunch delivery service to offices and homes, as this can also be a way to bolster sales. As a rule of thumb, most restaurants operate on a 40-40-20 percent basis, meaning 40 percent of the revenue covers food and consumable costs, 40 percent of revenue covers operating and overhead costs, and 20 percent of revenue is left as the pretax gross profit.