Mix flours, salt, and yeast in a large bowl.
Add water and stir until a shaggy dough forms.
Fold through the sprouted lentils, distributing evenly.
Cover and leave at room temperature 20-24 hours.
Dough will be well-risen, bubbly, and slightly domed. Turn onto a floured surface.
Shape gently into a round.
Place in a floured proofing basket or lined bowl, seam side up.
Second rise 1-1.5 hours (shorter than before — the dough is more active after 24 hours).
Preheat oven and Dutch oven to 230°C for 30 minutes.
Turn dough into hot pot, score the top, cover.
Bake covered 30 minutes.
Remove lid, reduce to 210°C, bake 15-20 minutes until deep brown.
Cool at least 1 hour.