Tincture, extract, for what we do here either word is fine. I personally would crush the coriander first if you haven't already, and chop the orange peel into short sections. Use enough cheap vodka, or other neutral spirit to cover the pieces. I would use a small diameter jar so the amount of spirit use is minimal, like a jelly/jam jar. I am wondering why you have put your beer into a secondary, but this time it will be to your benefit I believe. 4 ounces of spirit should be fine. Leave it 2 or 3 days, and then pour the whole thing into the secondary. The coriander and orange will continue to add additional flavor every day up to a point, as long as they are in your beer. Taste every day, and when flavoring is correct, cold crash for 3 days or as needed to clear to your liking. Rack onto priming sugar and bottle.
"Le petite de l'orange" translates into "of the small orange".