Atjar tjampoer is the Dutch word for Indonesian sweet and sour pickled vegetables (usually carrots and cabbage and many other shreds of unidentifiable plant matter).
Makes an excellent accompaniment to spicy dishes such as Nasi Goreng; the sweet and sour taste help counteract the sambal and trassi. Pickles of any kind (sweet, sour, dill, whatever) work almost as well, but don't give you that studly super-authentic feel.