"We gave an order to the restaurant."
Translation:Thugamar ordú don bhialann.
"Chuig" mean towards and implies motion. In this case, there is no motion. At least that is my understanding. Someone else might be able to confirm. There are 3 prepositions for "to" that i know of (chuig, go, and do) but they all are a bit different and are used in different relative circumstances.