"Jij doet de deur open."
Vertaling:You open the door.
It comes from 'open doen' and it's common in Dutch to use that construction when opening something. It's not incorrect to say, for example, "Ik open de deur" but much more commonly you'll hear "Ik doe de deur open" or Hij doet het hek open" (He opens the gate) or "Wij doen ons boek open" (We open our book), or Jij doet je mond open (You open your mouth), etc. The word open stays the same, all you have to do is conjugate 'doen.'
Thank you for your answer. It's very interesting to find this kind of sentence construction in Dutch as well.
Now I wonder: Is "doen" used as well like an auxiliary verb when speaking to small children in order to spare them the conjugation of irregular main verbs? Like a baby language?