After much testing, here is my new vegetarian polenta recipe.

1/4 cup polenta
1 cup brown vegetable stock (recipe follows)
salt pepper
1 tablespoon fresh lemon juice,
fresh tomato juice, or whey from yogurt.

Mix the polenta and stock in a microwave safe bowl. Add a little salt
and pepper, and the whichever of the acidic liquid you chose. Stir, and
cook on high, uncovered in the microwave for about three minutes.
Stir again, and notice how much liquid is left to be absorbed. Your
milage will definitly vary. I usually cook mine for about three more
minutes, but I have a very low power microwave. The best thing to do
is to cook in one minute intervals until polenta is thick and the
grains are chewy instead of crunchy. Let it rest for about one more
minute. Check the seasoning, and then you can eat it as is, or use as
a base for other recipes. (My next one is pizza with polenta crust.)
I add the acidic liquid, since I found that the vegetable stock is
very sweet from the browning. If you don't have a microwave, you
can put this in the oven (350 degrees for about 30 minutes).