Flat loaf :(
I'm a novice baker (baked maybe my 10th loaf) and I have an issue with my "tartine" style country bread: despite developing the gluten quite well and achieving a beautiful open crumb, the bread proofs more outward than upward.
The recipe is this: 715g water 200g starter 900g bread flour 100g whole wheat flour 20g salt + 50g more water
I did a 2 hour autolyse, 5 rounds of stretch and folds over 90 minutes (instead of over 3 hours, following the method "Tartine for dummies" on Youtube). Bulk fermented 24h in the fridge with not a lot of growth, shaping with reasonable strength and tension (I bought a high gluten bread flour, so the handling of this relatively high-hydration dough was pretty cool), 12h fridge proofing, seeing that it didn't rise a ton. So I gave it 5 more hours at room temp, which finally produced the right springiness.
When I dumped the loaves into the Dutch oven, they were quite runny again and baked into beautiful, but flat loaves.
My assumption is that I lost a lot of the strength and tension in the long proof at room temperature - but my starter didn't move much in the 4°C fridge, so I decided for the room temperature proofing.
When I baked my first few loaves, I added very small amounts of active dry yeast to help my young starter out - those loaves proofed considerably faster and had better ovenspring (I didn't lose all the tension as I was able to proof them in the fridge, and a lot faster).
Ideas? More starter? Try to get the starter stronger? (it did float, btw). Other ideas about the process?