Mix the flour and water in a large bowl, cover, and rest 30 minutes.

Add starter and salt, mix well, then perform 3 to 4 sets of stretch-and-folds over 2 hours with wet hands.

Turn dough onto a lightly floured surface, shape into a taut round, and place seam-side up in a floured banneton or bowl lined with a floured towel.

Cover and refrigerate 12 to 18 hours until puffy and the dough slowly springs back when poked.

Preheat a Dutch oven at 450°F (230°C) for 30 minutes. Invert dough onto parchment, score, bake covered 30 minutes, then uncovered 15 to 20 minutes until deep golden. Cool completely on a wire rack.