Schedule C: COGS/inventory in food service

Hi! I'm confused as to how to complete Part III of Form Schedule C: Cost of Goods Sold. I own a mobile food stand and, in the food industry, COGS represents a slightly different principle, often only mentioned as a metric for menu pricing. As the owner of a seasonal/intermittent food business, I do not have "inventory" per se - just partial "inventory" of ingredients (that is, opened). I guess I'm just confused about how the terminology is used.

 

As I understand it, I just need to enter food costs and any disposable food containers/utensils that go out to the customer under line 38: Materials and Supplies. Do I need to be completing any other sections? I don't think "inventory" here refers to small-scale perishable inventory, such as an open bottle of soy sauce, or something - does it? Thanks!