Before I scare anyone away from udon, the link Stephanie includes below shows a MUCH easier way to make them.
single bento boy's link in this thread: http://www.justbento.com/forum/foodie-movies  got me watching the movie "Udon"
Within minutes I started drooling and hankering after the kind of udon I'd eaten in Takamatsu.
I went back to a recipe I'd used before: http://search.japantimes.co.jp/cgi-bin/fg20010701rl.html  - worth reading to get an idea on how the weather affects the amount of salt you should use
But I'm not convinced this describes the best way (I largely ignored everything this time and came out with my best tasting udon yet!)
One change was that I used 100% strong bread flour, not the mix suggested - but this was because I just didn't have any cake flour or regular all purpose flour. So I still haven't worked out yet what the optimum blend is for home made udon.
So far I've learned that the initial dough needs to be really 'dry'. I nearly managed it yesterday, but it wasn't quite dry enough (something that only becomes apparent when it sticks to the plastic bags or at the end when you try to separate the cut strands). I couldn't see how I could get the dough dry enough and then knead it by hand. Today I found a video that shows how it's done. So I tried making Udon again using this resource and I'm satisfied enough to want to share my findings here.
Taking my cue from that initial recipe, and bearing in mind that my family's tastes are for udon with a very firm 'koshi' bite:
1/2 kilo white bread flour (I suspect that incorporating a less glutinous flour, such as cake flour, will result in noodles with a softer texture - the Japan Times instructions about mid-gluten flour are probably a better way to start)
225 ml water (I used filtered water)
3 teaspoons salt (I prefer sea salt)
Empty the flour into a large bowl. Dissolve the salt into the water and incorporate it into the flour. You should end up with a 'dry' dough that can barely hold itself together. If there is too much water, add more flour to compensate.
Form the dough into a ball by scooping the lot into a small plastic bag and pushing everything together inside it.
Place a mat or towel onto the floor, transfer the ball of dough into a large, clean, sturdy plastic bag (be sure there are no logos that will transfer ink onto the dough) and place it onto the mat. You can add another towel or mat onto the top of this.
In your bare or stockinged feet, press out the dough into a flat circle. Roll up the flattened dough and tread it out again. In the clip the dough is flattened and rolled up again a total of five times.
Remove the the trodden dough from the plastic and transfer it to the large bowl. Knead it for about a minute and form into a round ball (or two round balls). Put into a plastic bag and leave to rest for at least 10 minutes - I'd suggest an hour minimum.
This is the part where you tread out the dough ready for rolling. Put the dough ball back into the sturdy plastic cover and tread out as perfect a circle as you can. The clip shows you a good technique to doing this, but the circle you end up with will be smaller as less flour has been used. Please read the next part as you may want to make two circles at this stage.
Rolling out udon is very different to rolling any other pastry I've come across. You need to form a 'swiss roll' with the rolling pin in order to get the surface area of the dough to increase. The clip does an excellent job of showing how it's done. Just bear in mind that with a shorter 'Western' rolling pin it's easier if you only try rolling out a portion of the dough at a time, my tip is to aim for a rectangle rather than a square in order to get long noodles.
With the cutting - when folding the rolled dough be sure that each layer is generously dusted with flour so that it falls apart easily after cutting. Try to do this somewhere cool away from any heat sources - prising apart 'melted together' noodle strands individually is really tiresome!
As the rolled out dough has been folded to make the cutting easier, the main task now is to try and cut it at 90degree angles to the edges and folds of the dough and make the cuts uniform in their wideness. The sharper and bigger the knife, the easier it is. So far, I've never done this part with a wooden block (as the clip shows) and just used my eyes as a guide. My noodles are usually a bit 'kinky' but that's fine for now, eventually I hope to improve. Udon expands a little in boiling water, so don't make them too wide (perhaps half the width of your little finger, or less if your hands are large).
Separate the noodles into long strands and shake off any excess flour. Arrange them into piles for boiling.
Cooking - I don't know what the optimum water to noodle ratio is, but I do know that the noodles shouldn't be too crowded in the pot. Boil up a generous amount of water in a large pot, and if that pot isn't huge, put half the noodles into the boiling water. Gently stir once in a while so that the noodles don't stick to the bottom. Generally, they seem to take 13 to 14 minutes to cook, but do test them first to be sure they're ready.
Once done, transfer to a sieve/colander and run under cold water and rinse them thoroughly. This, apparently firms them up. You can serve them cold or put them into hot water or broth for at least ten seconds to warm them up again.
There must be hundreds of ways to serve udon. However, as these are freshly made and therefore 'special' you might like to try them this way: Drop a drained portion (warm or cold) into an empty bowl, add some good quality soy sauce, a dribble of rice vinegar, some freshly sliced spring onion/scallion and perhaps some toasted sesame seeds.
I hope I've made it clear that I'm very much a novice when it comes to making udon. Despite the instructions being so long-winded the process isn't very hard and it's a lot of fun to do (I can't wait to be doing this with my own child). It would be wonderful to find out how other people make udon, I'd love to learn from others' experiences. Any comments on the techniques I've described would be very welcome.