Can say that "I over-ordered" food in a restaurant as a client?

Solution 1:

I over-order - place too large an order (OED) - more often than I like to admit.

Over-ordering is a very natural, idiomatic way to describe the consequence of having eyes 'bigger than ones stomach'. I find Indian food particularly troublesome in this respect.

1977 D. Bennett Jigsaw Man v. 106 ‘You aren't liking your good grub.’ ‘I think I over-ordered.’(OED)

1998 Zest Sept. 38/2 (caption) My perfect woman..has to be able to cook a mean beef stroganoff and not over-order Indian takeaways. (OED)

The OPs example phrase would usually be said as 'I('ve) over-ordered.' (i.e. 'food' is understood).

Solution 2:

The sentence is grammatically correct but it's not something most English speakers would say.

Most likely they would say they ordered too much.