After about 800 miles on the vendetta, I'm starting to feel like one day I will be able to ride no-handed and pedal. I think it is largely a matter of intentional practice, ratz is right, just try it for a few minutes on every ride. Someone else (dsteng?) mentioned pushing outward a little with your foot as you push to reduce the pedal steer and that also seems to help.
I can ride no-hands and pedal for 10 sec or so right now, including catching a minor wobble or two, but eventually I get too-big a wobble and I have to grab the bars. It is enough that I can see the point coming where I will be able to catch all wobbles without going to my hands.
Fun stuff.
Well, it took me a few thousand miles to get somewhat comfortable riding
one-handed on my first MBB bent (65 deg steering angle, short trail), and the prototype I've been mentioning was not *that* much different due to not enough trail and huge bars that threw weight distribution out of whack (it nearly self steers OUT of the lean instead, like most non-MBB recumbents with tiller steering - reason why most of them, while quite stable, are nearly impossible to ride no-handed).
On my last prototype, however, (90 deg steering angle, 6cm trail) I've managed to 'coast no-handed' on my second ride, and it took me only a few more rides to pedal no-handed - still a bit wobbly like you said, but otherwise quite doable (it actually took me longer to learn to ride no-handed on DF!).
Geometry matters a LOT... especially if your kineasthetics suck