Wow! I am so sorry to hear about all that work for not. How terribly frustrating. Especially since it was a sour and you fed the starter so well! I've never heard of not preheating the oven though. Did you add salt? Did you mix the heck out of it to develop the gluten?
Thinking about the 12 steps of bread making,
1. Scale your ingredients...did you confirm that all was correct?
2. Mix. Again, mix the heck out of it. For at least 10-15 minutes. Did any of your recipes call for a "window test?"
3. Rest. Self explanitory.
4. Punch. (not literally, of course.)
5. Scale. (I'm sure you only did enough for one batch, right?)
6. Round. Could you have kneaded too much at this stage?
7. Rest. How long did you let it rise?
8. Shaping/panning. Not a whole lot can go wrong here.
9. Proof. Here's another spot that could make it hard. Too long and the bread loses flavor, not long enough and the dough tends to tear.
10. Bake. I'm thinking that clay thingy could have something to do with it.
11. Cool. What's done is done.
12. Eat/store. I'm so sorry! Do you have any of your starter left to start over?
