This little herb sprouts tiny leaves widely spaced over its long, plump little stems. Rau ngo om is chopped or torn up whole, stems as well as leaves, and then added to soups and curries at serving time. With its petite oval leaves attached to the stem at intervals, from base to tip, rau ngo om looks like a sprig of thyme that has been magically inflated. But the resemblance ends there; don’t try to replace it with thyme.