This version is converted but not yet test-baked. Trial-run checklist for the first bake: (1) Water — 430 ml is the starting estimate; the mixed dough should be soft and shaggy, not stiff, so add water 1 tablespoon at a time if it looks dry, and note how much the loaf actually took. (2) The rise — check the dough at 3 hours, not just 5: psyllium keeps hydrating as it sits, and a dough that tightens up early may not want the full rise. (3) The crumb — slice only when fully cool and check for gumminess; a gummy center means the loaf needs the covered bake extended by 5 to 10 minutes next time.
Powder versus whole husks: this recipe is written for psyllium husk POWDER. Whole husks are weaker; if that is what you have, use 1 1/2 tablespoons plus 1 1/2 teaspoons (about 10 g) and expect a slightly looser dough.
The flour blend matters: use a plain blend with NO xanthan gum already in it, since psyllium is the binder here.
A 4- to 5-quart Dutch oven fits this loaf. Cast iron holds the heat best.
Storage: wrap and keep at room temperature up to 2 days. Refresh slices in the toaster.