>>1
A lot of bento box food is fairly basic: rice, some meat and/or fish, vegetables, maybe something else as a side or garnish. I don't see why you couldn't use basic steamed or vinegared rice; for effect and color, add some nori flakes and/or shaved bonito and an umeboshi (pickled plum). You can make a basic grilled fish filet piece, like salmon, whitefish, mackerel, swordfish, tuna, whatever you like using a marinade of soy sauce, a bit of pepper, some mirin or sake, and dashi broth. After marinating the fish, you can grill it up, and for an added touch, you can fool around with making a reduction out of the leftover marinade. Never tried it myself, but in theory, it should work.
You can buy kimchi and other pickled vegetables at Asian markets. I like it really red and spicy... I am so totally craving the stuff now.
I'll see what else can be dug up, but I might just buy that book...