Total calories (approx): 455 (how calories are calculated) 
Time needed: 25 minutes total (15 the night before, 10 in the morning)
Gyuudon or beef bowl has become more and more popular outside of Japan. In its basic form, it’s beef and onions or leeks simmered in a savory-sweet sauce, served on a bed of rice. It can be awful if made with bad, gristly beef, but very good if made with good, tender slices.
This version of gyuudon cuts the calories and adds a lot of fiber by substituting some konnyaku for the beef. Konnyaku is made from glucommanon, the same as shirataki noodles. I’ve explained them both in detail on Just Hungry . They are both great sources of dietary fiber, and have practically no calories.
Shirataki noodles are actually used quite a bit in gyuudon recipes, but I’ve used konnyaku here because it has a more substantial, chewy texture. It has no flavor to speak of of its own, so it absorbs the flavors of anything it’s cooked in like a sponge.
The top trick used here is setting aside some ingredients for a dinner dish to make the main part of this bento simultaneously. I made this gyuudon mixture at the same time I made hayashi rice  or Japanese beef stew a couple of nights before. Two of the main ingredients, beef and onions, are the same after all. So I sauteed the onions for both, then made the gyuudon on the side in a separate pan. So why not just use leftover hayashi rice for the bento? Well, you can of course. (Actually I did have a hayashi rice leftover bento once this week too.) This way you can have totally different tasting bentos using almost the same ingredients!
The greens can be anything you like - spinach, pak choy, etc. I used some of the last leaves on our Swiss chard plants in the garden.
The little pink things you see in the photo are whole pickled radishes - I just put some radishes in a vinegar-sugar-salt marinade for a few days in the fridge. Any pickles will do here - they are there mainly for color and texture contrast.
For the beef mixture:
This makes enough for 2 portions.
A handful of green onions for color (optional)
A small bunch of greens of your choice - spinach, pak choy, chard, etc.
pickles of your choice
It’s important the heat the beef mixture through in the morning, especially if it’s been in the fridge longer than overnight.