Part of the problem is that the process for making gluten bread requires the gluten to develop. Not so for gluten-free. If the starter is mature enough then it will generate air, and we hope to capture that air with flax / etc. Oven spring is caused by the air bubbles expanding rapidly.

So, then: we want to allow the rising process to be constrained by the starter’s progress through the available material. Yesterday we saw that a quick knead led to more activity, which makes sense. Perhaps the idea is to understand firstly how long it takes the dough to ‘stop’ rising. At about 65% of that time, split and shape. It would be good to be able to stretch & fold à la Tartine, but I’m not sure how fragile the flax strands are. Preheat the oven and pan: cross fingers and hope.