The full recipe is over on A Letter From Home, so rather than repost the entire thing I'll just do a quick summary:
Pork Medallions for 1
Cut the tenderloin into medallions about 1cm thick. I generally manage three or four medallions per 150g of tenderloin. The original post gives a trick to cutting the tenderloin: there's a white sinewy bit on the underneath, which you can cut through to from the top. You can then relatively easily shear/scrape the meat off the sinew.
Pick three of the medallions, and freeze the rest (spread out rather than all in one stack so you can easily separate them later). When you want to cook some of the frozen ones, take them out the night before and put them with some of the marinade in a bag on a plate in the fridge.
Mix up a marinade of some olive oil, garlic, and pepper. If you're feeling fancy the original post suggests crushing peppercorns, but I just grind some in (I also almost never remember to buy actual garlic and so just use garlic granules!). Smear the pork with the marinade and let it think about things for a while.
To cook it, just fry the medallions in a nice hot frying pan for 3-4 minutes a side. Simples!
After frying them, pour a bit of wine or cider or veg water or something into the frying pan and let it bubble for a few moments. Stir in a small dollop of cream and give it another moment to think about things and turn a nice light brown colour, then pour over your medallions (and pasta or whatever).
It's a nice easy recipe to do and doesn't take long either, though I do have to remember to take the extra medallions out of the freezer the day before I actually want to cook them. Normally to make the sauce I just stir in some of the water from the pasta-and-veg pan, but today I happened to have a mixed fruits Kopparberg cider which I thought I'd try instead. The result is... interesting, but I think a plain cider would have a less strong taste and probably work better. I'll have to remember that next time!