This is a very simple yet quite pretty bento decoration that I saw in a Japanese magazine. Just take slices of cooked carrot (I just boiled them for a few minutes in salted water, but you could use the orange carrots recipe  too), stack on top of a slice of cheese, and cut through with a small cutter.
Then pop out both cut-out pieces, and insert the cheese cut-out into the carrot circle. The result is a nice bi-colored decorative piece.
You can of course use the cut-out carrot part too.
Just remember that you need to cook the carrot slices before you cut them out, since of course you can’t cook them after inserting the cheese! (Yes, I learned this by trial and error.)
I used cheese that I sliced to to the same thickness as the carrot slices. You could use pre-sliced cheese, but the carrot slices would have to be quite thin to match. The decorative rounds look the nicest if the cheese and the carrot are the same thickness. (You could experiment with a double-layer of sliced cheese.)
Incidentally, I found the tiny cutters used for this in the craft section. They are sold as polymer clay cutters, and are about 1 cm / less than 1/2 inch in diameter. I don’t use them for polymer clay of course - they’re reserved for food.