While not as carefully collected, organized and commented on as Japanese Zen Koans, there is a Theravada tradition of practicing with a dharma, question or riddle, e.g., “What is the place that does not come or go or stand still?” “If the Buddha was never born, where is he now?” or “How can we live so as not to be seen by the king of Death?” The monastic forest traditions of Thailand (e.g., among the lineages of Achaan Mun, Achaan Maha Boowa and Achaan Cha) have also preserved a variety of practices using sacred mantras for concentration and insight; sometimes we find these mantras used in conjunction with rituals of protection or exorcism. In some Burmese and Thai meditation traditions there are practices that involve focusing on charka or energy centers in the body and other practices involving energy transmission from teacher to student (e.g., among the U Ba Khin tradition in Burma and at Wat Paknam in Thailand). While the practice of vipassana might be highly effective, it would be a pity to ignore this wide variety of skillful means.
http://www.insightmeditationcenter.org/ ... theravada/
I searched google for the individual questions and for "dharma question" or "dharma riddle" but I am unable to find nothing about this particular form of practice within Theravada. So I was wondering if anyone here has had experience with anything like this in a Theravada setting or has at least heard about it.