[gradschool]

Wouldn't it be more accurate to say that you need NAND gates and a clock? Identifying a minimal set of primitive components necessary to implement a self-timed computer would be a more interesting problem.

[raverbashing]

You can build your clock using, guess what, NAND gates, one capacitor and one resistor (not a great clock source, still).

You also need a power source, so you can say the only digital component you need are NAND gates.