I use a General Finishes salad bowl finish, which is a non-toxic
and low odour varnish. 3 coats generally produce a reasonable shine
that isn't too glaring. I find that box elder needs a toughish finish.
For salad bowls I have started using Osmo finishes. The trouble is that
they are expensive but you need the larger tins (500ml) of it to store
in "Stop-loss" bags as I have lost too much due to gelling in the small
cans.