I am always on the lookout for vegan/vegetarian protein recipes that are bento friendly, and this flat oven baked loaf is another one. It's called triple-soy because it has tofu, edamame and miso in it. It has a very dense, rich texture with a sweet-salty glaze. One or two small squares are quite enough for a bento. It may fall apart a bit during transport, but that doesn't affect the texture or flavor. If you can, put it in its own compartment in your bento.

Shuumai or shumai dumplings （焼売）are a standby for dim sum, and are very well suited to bentos. They are small, taste good cold, freeze very well, and are a lot easier to make than gyoza dumplings.

You've probably encountered shuumai dumplings in the freezer section of Asian or Japanese grocery stores. Frozen ones are usually pretty good, but if you make them yourself you know exactly what you put in them. I just make a double batch whenever I decide to make shuumai for dinner. Just follow along with the photos and you'll be turning out lots of shuumai yourself.