Phrases Ordering Food and Drinks

Could I have a side of...

Meaning

Ordering a side dish

Translation language

John: I'll have the steak, please.
Alice: Excellent choice. Anything else?
John: Yes, <b>Could I have a side of</b> mashed potatoes?
Alice: Certainly. And perhaps a vegetable? <b>Could I have a side of</b> green beans as well?