What I (try to) teach in the Alps (for tight, technical, slow-speed switchbacks):
Start super-wide. Ridiculously wide. If this requires riding over rocks, roots, cabbages, etc, do it!
Outside foot forward.
Stay wide until your cranks are about level with the apex.
Turn like you mean it! Turn the bars, rotate your hips, shift weight to the front wheel (as much as possible when it's steep & techy).
This should be enough to get you round, but you can get some extra help from making a quarter rotation of the pedals (so that your outside foot is now down, this also helps keep you moving when you might stall). With your outside foot now down and you more or less past the apex, driving the outside foot will help to get the back end of the back round (a bit of low-speed drifting might result if the surface is wet/loose/rock slabs/cow poo/whatever).
Most importantly, keep your eyes locked on where you want to go, all the way round – look for the apex on the way in, then look for the exit as soon as you can.
When you move to the outside to enter the turn, if you can do this dynamically, with an up and down weight movement (like a skier turning) it helps a lot, as you can get the bike leaning the right way – if you just steer to the outside, you'll probably find yourself leaning the wrong way and hence slow down your turn initiation.
