The Cost of Food in a restaurant is a Cost-of-Goods Sold to enter these items please follow the steps below:
Log into TurboTax Online and access your Tax Return through the Timeline
From your Welcome Page in the upper right-hand corner find the Search Box and type Schedule C (capital Sand C) hit enter and from the search options click on Jump to Schedule C
Then (assuming your business has already been set up in TurboTax), you'll want to click Edit next to your business and then scroll down to the Inventory/Cost of Goods Sold topic and click on Start (or Update).
You will select, Yes I have an Inventory to report and TurboTax will walk you through the process of entering these expenses.