service hatch; pass-through
A small opening or counter used to pass food and dishes between a kitchen and a dining area, common in restaurants, cafeterias, and home kitchens.
Please place the dishes on the service hatch when they are ready.
The pass-through in this cafeteria is wide and easy to use.
Compound of 配膳 (はいぜん, 'serving food, setting a table') and 口 (ぐち, 'opening, mouth').