This casserole is simple and delicious, and makes a perfect snack during a picnic (bento anyone?)—you should use it as a basic idea for a casserole, since the pasta sauce is the stable and the most important piece of the meal. It's also a very tweak-able recipe! :-)
This is one of my signature dishes—it's delicious, rich and hearty, and goes well with any kind of base: pasta, potatoes, and rice just taste superb together. My secret to the intensive, flavorful sauce is the triple reduction of the ingredients' fluids, due to cooking in batches and mixing in specific order. It takes some time, but the result is so much worth it! :-)
Bento is not only rice, but also other ingredients, like... pasta. This recipe came to life when I had some uncooked beef left-overs and just wondered what to do with them. Cooking them as a part of bento was a great idea!
You can buy thin beaf slices in some grocery shops or butchers. They may be called minute steaks or quick steaks and are a great ingredient that you can use to make a quick donburi (a rice bowl with meat and vegetable toppings). It's so fast to prepare, that you can do everything in the time it takes to cook the rice!