Total calories (approx): 445 (how calories are calculated) 
Time needed: 15 minutes in the morning, 20 the night before
This is the ‘skinny bento’ featured in Skinny Bento vs. Not So Skinny Bento .
I made everything in advance the night before except for the tamagoyaki, but I could have made that in advance too. This can also be made in the morning in about half an hour, except for the task of marinating the chicken teriyaki - if you have to do that too, add another 10 minutes or so. (I’d cut up and marinate the chicken, go and shower and stuff, then return to finish the bento.) All in all though, I think this bento is more efficiently assembled by doing almost everything the night before, as I show here.
I’ve already given the recipes for bite size chicken teriyaki  and tamagoyaki , so here I’ll note down the recipe that is barely a recipe for the bean sprouts with umeboshi (moyashi no ume ae). This is a refreshingly crunchy and very low-calorie sort of side salad, which I like to serve with a meat dishes.
If you want to be very neat and professional, top and tail the bean sprouts. I usually don’t bother…though for company, I might take off the stringy long root.
De-stone the umeboshi, and chop or smoosh up the flesh to a paste. Add a few drops of the umeboshi juice or ume vinegar to loosen up the paste a bit.
Blanch the bean sprouts in boiling water for about a minute, then drain and rinse under cold water to cool. (The two large handfuls will shrink down quite a bit, to about 1 cup.) Drain well, and mix with the umeboshi paste.
This does not freeze successfully.
I like to use blanched spinach a lot in bentos. In Japanese cooking, spinach is rarely eaten raw; its most often blanched, then various flavors or sauces are added to it. In Japan full stalks of spinach (with the roots attached in many cases) are common, but here it’s a lot easier to buy baby spinach. Baby spinach blanches in seconds - boil any longer and you get green mush.
When I buy a big bag of ‘pre-washed’ baby spinach leaves, I wash it first just in case. (It’s not gritty usually, but you never know…I once found a tiny snail in a ‘pre-washed’ bag! At least I guess it was organic…) Then I toss it in a big pot of boiling water. As soon as all the leaves are in the water, I immediately drain the spinach into a colander, and then refresh it by dunking it into cold water.
I then squeeze it out with my hands into a small log (that big bag will shrink to a pretty small log). I cut the squeezed out log into pieces that are about the height of the bento boxes I use. The little cut up logs can be frozen, and taken out as needed.
Haiga-mai is white rice with the rice germ intact. It isn’t as fibrous as brown rice, but has more nutrition than plain white. You can find it more often these days at Japanese grocery stores. (See Looking at rice .)