Drawboring is an old-school technique from back when glues weren't what they are today. Similar to the pegged M&T joint that you used, but where the holes in the tenon are purposely offset perhaps 1/16" and the pegs don't start out round and are usually riven, and are tapered at one end. When the joint is assembled and the pegs driven home, the offset holes suck everything together and the riven pegs prevent any rotation or movement. From what I've gathered, the glue is almost optional! I'm not quite that trusting, though