In a large mixing bowl, combine the flour, salt, and instant yeast. Whisk to mix thoroughly.

Add the lukewarm water and active sourdough starter to the dry ingredients. Stir with a wooden spoon or spatula until a shaggy dough forms.

Cover the bowl with plastic wrap or a kitchen towel and let the dough rise at room temperature for 12 to 18 hours until doubled in size.

Lightly flour a clean surface and turn the dough out onto it. Shape the dough into a round loaf without deflating it too much.

Place the shaped dough on a piece of parchment paper and cover it with a kitchen towel. Let it rest for about 30 minutes.

Preheat your oven to 450°F (230°C) with a Dutch oven inside for about 30 minutes.

Carefully remove the hot Dutch oven from the oven. Lift the parchment paper with the dough and place it into the pot. Cover with the lid and bake for 30 minutes.

Remove the lid and bake for an additional 15-20 minutes until the bread is golden brown and has a crispy crust.

Remove the bread from the Dutch oven and let it cool on a wire rack for at least 1 hour before slicing.