First, you don’t need a special “bento box”. A glass or plastic food storage container, or used take out container will work just fine. You want it to be fairly shallow with a secure lid. Hint: if your lids get wonky like ours do, wrap a rubber band or two around the finished box.
Remember the “tasting menu” idea. Include as many small bites of different colors, flavors and textures as you can. Variety makes the combination more interesting.
Paper, foil or silicone cake/tart cups can be used to separate different foods. Avoid sauces and wet/liquid foods. But if you must, use a box with dividers, or a small separate container for liquids.
Include something starchy. In Japan the starch is almost always rice. But when you use Yumbini, you get rice PLUS a protein food! Other grains, pasta, potato, and bread work too. Hint: Mold the Yumbini into pretty shapes by pressing it firmly into a cookie cutter then lifting the cookie cutter off.
Include a protein food. In addition to Yumbini with all those great beans and lentils, try fish, egg or tofu (popular in Japan), or nuts, seeds and cheese.
Include a colorful array of vegetables. Vegetables in Japanese bento are pickled or pre-cooked in a seasoned broth for perfect flavor and texture. Cooking/pickling also makes the vegetables last longer without drying out or wilting. Easiest for American cooks is simply boiling vegetables for a short time (3 minutes) in lightly salted water. But there are many other pre-cooking techniques you can try: roasting, stir fry, microwave, or making a “quick pickle” by salting vegetables and draining out excess liquid.
Consider including colorful fruits. Japanese bento does not often contain fruit. But with the abundance of fruit available, it would be a shame to leave it out. Focus on small fruits with edible skin like grapes, peeled orange/tangerine sections, strawberries, blueberries, cherries, plums and apricots. Avoid fruits that need to be peeled or cut, such as apples and bananas, as the cut edges will brown and be unattractive. Hint: if apples and bananas are all you have, put some lemon juice on the cut edges to reduce browning.
It may be easier to make several bento at the same time. One package of Yumbini will make at least two or three bento. Consider using leftovers. For example, last night’s pieces of fruit, cooked vegetables, bread or casserole-type dishes work great.
Pack your bento box tightly so the components don’t move around. Part of the excitement is so many goodies together in a small space! (You may find the box does not need to be as big as you thought.)
Most of all, have fun and experiment! You will get better at bento-making, and think up more ideas as you go along!