Cu the wiener sausages to form the bottom part of a cute acorn. Choose shimeji mushrooms that are a little bigger then the sausage to use as the tops of the acorns.

Heat a very thin film of oil in a frying pan. Add the mushroom caps and sausage bits. Cook the mushroom caps carefully, turning them occasionally. Season the caps with a tiny bit of salt and pepper.

Put the cooked bits on a plate lined with tissue paper to absorb any excess oil, and leave to cool down.

When the pieces have cooled down, poke a hole through the middle of a mushroom cap, then through the top of a piece of sausage.

If there's a gap between the mushroom cap and the sausage, cut off the stem part of the cap or slice off the rounded top of the sausage.

This is how they look lined up in a large multi-person bento box. They are great as space fillers in regular one-person bento boxes as well.