I suggested the complete meal as a way to add a little depth to the contest. Food items are so incredibly small and easy to make, you'd figure doing a few would be nice. To tie them together, you use the meal theme.
Beyond that we need to discuss what size though. Normal CV item inventory icons are 16x16 I believe. I think that would be reasonable, and help make them faster to create. Castlevania has rarely ever exceeded that size for items, even in the classic games.
The icons in game also do not use an excess of 16 colors, which is very reasonable at that size as well. I would like to see that as one of the rules. Color management is a very very key component to style and art in general, especially pixel art. To be explicit, that means 16 colors per each individual food item sprite.