It's not actually called "niku-jaga" in the index of Personal Trainer: Cooking. Instead they refer to it as "Braised Beef and Vegetables" -- perhaps to convince an American audience that it's familiar and not frightening. Nonetheless, the notes refer to this as niku-jaga, the homestyle Japanese beef-and-potato stew.
The main difference between this and Western-style stews is the use of Japanese ingredients in the braising liquid -- particularly dashi broth. And it's one of the areas where PTC surprisingly disappoints.
Ingredients: Beef and potatoes, of course -- with more potatoes than we'd see in a Western-style stew. (It must be remembered that the Japanese, by and large, aren't big on eating meat.) Onions and green peas, also not out of the ordinary for a stew.
Dashi broth, though -- this is where I got surprised. PTC will tell you how to make beef/chicken stock for its French recipes, which is a good idea and definitely good to know. It does not, however, tell you how to make homemade dashi stock. It tells you that it's made from bonito flakes and seaweed, and that it's easy to make -- but that's it. No recipe whatsoever.
There is, of course, a workaround. I happen to have an authoritative recipe for dashi -- from Shizuo Tsuji's Japanese Cooking: A Simple Art. This recipe gave me the excuse to try it out, with some pantry items I got from the last time I went to Edgewater, New Jersey, to visit the Mitsuwa Marketplace. In 20 minutes I had a litre of dashi, a little heavier in flavour than what the book recommended but still usable for this PTC recipe.
Techniques: I did get another surprise, but this one was somewhat better: the directions explained how to make a drop lid.
Traditionally, this would have been made of wood, and if you ever watch a Kurosawa samurai movie when they cook with a pot, you'll see that the lids are made of wood. That's because they're designed to float on top of the ingredients, rather than just sealing up the pot; this helps concentrate the cooking liquid's penetration power, apparently. PTC recognizes that not every American household is going to hop onto the Internet to buy a drop lid, so it shows you how to make one out of aluminum foil.
The other steps involved are fairly straightforward: cook the onions and potatoes together, then brown the beef in the same pot, put the onions and potatoes back, pour in the dashi, season with sugar, mirin (which is much easier to get these days) and soy sauce, cook with the drop lid for a short period, then serve.
Results: I think maybe next time I won't use as much sugar as the recipe specifies, but the dashi does add a semi-smoky flavour to this stew. I think I might also add some cornstarch as a thickener, because it is a touch more watery than I normally prefer for a stew.
I'm tempted to give PTC a fail on this one, mainly for not telling the user how to make the required dashi, but the dish tasted well enough that I'm willing to let this particular faux-pas slide.