订餐 is a separable verb-object compound (离合词) meaning 'to order a meal' — typically used for food delivery, takeout, or reserving a meal at a restaurant. Because it is a 离合词, the verb 订 and the object 餐 can separate when adding aspect markers, measure words, or duration: e.g., 订了餐 (ordered a meal), 订过一次餐 (ordered a meal once). Do not place another object after 订餐; the meal itself is already the object.