First off, I haven’t actually uploaded a complete bento here in ages, so here is one! It features Japanese Scotch eggs, which you see in the near-most box. (The rest of the bento consists of cucumber slices with sea salt; a carrot and celeriac salad; onigiri with umeboshi filling; banana and mini-cupcakes. The whole bento is about 1100 calories - I intended it to be for 2, but ended up eating the whole thing by myself!)
The original Scotch egg  is a British pub snack, made by wrapping a hardboiled egg in sausage meat and deep frying it. The Japanese version uses a ground beef/pork meat mix, and is either deep fried, panfried or baked in the oven. I usually bake them or panfry them, though deep frying is best if you want perfectly round Scotch eggs.
Japanese style Scotch egg is considered to be rather retro in Japan these days. They are typical of yohshoku or youshoku, Japanese-style Western cooking, where foods from the West have been adapted (mostly in the post-WWII period up to the 1970s or so) to suit Japanese tastes and available ingredients. (More about yohshoku .)
I rather hesitated to post this recipe since it doesn’t quite fit the usual criteria for recipes here. It takes some time and effort to make, so it’s not practical for a busy morning. It’s not very low in calories. And, it doesn’t really freeze well, because frozen hard boiled egg turns rubbery (though I have frozen it on occasion), so it’s not even a good make-ahead staple item! Other than that though, it is quite delicious at room temperature, so very well suited for bentos. You can make a few and keep them in the refrigerator for 3-4 days. Or make them for dinner and leave one for next day’s bento! That bright yellow and white egg against the brown of the meat is very cheery.
Update: If you found your way here from this entry on the Guardian Word Of Mouth blog , which in turn references an entry on the Chowhound forum , Scotch eggs are categorically not a staple of the Japanese New Year feast (osechi). It could just be that the Chowhound poster who said this just happened to encounter it at some time, in someone’s house. Hey, my aunt liked to serve mounds of vegetable tempura at New Year’s to feed a crowd easily, but tempura isn’t really a traditional part of New Year’s in most households either. Maybe your aunt likes to serve her special coconut cake or something at Christmas, but that doesn’t mean that coconut cake is a Christmas staple in most households. This is how erroneous information spreads on the web, I guess. Anyway….enjoy this very Japanese recipe with English roots!
Amounts are for 4 Scotch Eggs. Each is 450 to 550 calories, depending on how fatty the ground meat is and your cooking method. (You can make one, and pack just one half per bento. Even a half is quite substantial.)
If using an oven, preheat it to 200 °C / 400 °F.
Combine the meat, onion, raw egg, bread crumbs and seasonings in a bowl. Mix well with your hands until the meat gets paste-like and a bit sticky.
Divide the meat mixture into 4 portions. Flour the surface of a hard boiled egg.
Take one portion of meat and spread it out on your palm. Place a floured egg on top.
Carefully wrap the meat mixture around the egg.
Completely surround the egg with the meat mixture, and form into a ball with your hands.
Lightly flour the surface of the meat ball.
Repeat with the rest of the meat mixture and eggs.
If you’re going to bake these, put them spaced well apart on a lightly greased baking sheet (or line the baking sheet with a silicon liner or parchment paper). Bake 20 minutes, then turn and bake another 15 to 20 minutes.
If pan frying, heat up a large frying pan with a little oil. Put in the Scotch eggs, and fry them on one side until browned, then turn to brown the other side. Keep turning until all sides are browned. Turn the heat down to medium-low, cover the pan with a lid or a piece of aluminum foil, and continue cooking until the meat is done, turning a couple of times. This takes about 20 minutes total.
If deep frying, do so in medium-hot oil that is deep enough so that the Scotch eggs are at least half immersed. Deep frying takes the least time, about 10 minutes, but it is the most caloric method, and cleanup is messy (as it is when you deep fry anything meaty).
When the Scotch eggs are done, let them cool down before packing in a bento box. Cut in half to expose the egg inside. I like to brush a little ketchup on the cut sides of the meat part and a little on the outside, but this is optional.