Here's the method I used to make a sourdough starter. I don't have the exact
recipe in front of me (I'm at work), but here's the general idea: grate a
medium potato and add it to a jar with a tablespoon of honey (I'm sure other
liquid sweeteners would work, too). Add enough flour to form a soft (but not
dry) dough. Cover the jar with cheesecloth, or you could poke holes in the
jar lid. The point is to prevent something falling in, while letting the air
circulate. Leave on your counter and stir in the morning and evening until
it starts to smell sour, about 3 days depending on your climate. A greyish
redolent liquid will start to form - this is fine, just stir it in. If you
get mold, throw out the starter and begin again. Once it's ready, put in a
container and refridgerate. This is very easy and makes a great tasting
sourdough. I've had mine over 3 years and it just keeps getting better!
Just a note about e coli and berries, so people don't think it's something in
the berries that breeds e coli (someone mentioned this a few digests ago).
Here's the way it's been explained to me: the issue is food on the ground (in
New England the issue has been strawberries and fallen apples that are used
for cider) that gets exposed to cow manure infected with e coli, usually as a
fertilizer or through run-off water from a neighboring field. So the source
of e coli is still animal (and that's why it's most common appearance is in
beef). In terms of all other food-bourne bacteria, I agree with Mike, Bev,
and others who have posted on this issue: wash your fruits and veggies, throw
things out that smell bad, and use your common sense and you should be fine!