Vegetable Bolo

"Vegetable Bolo" (or vegetable balls) are a kind of mini-cookie for
children. More common are the egg balls (tamago boru) which are
extremely tasty, but I've taken quite a liking to the veggie ones
which are a mix of three types: pumpkin, sweet potato, & a kind of
spinach. Sounds weird, I know, but these are t-a-s-t-y.