In a medium bowl, combine yeast, sugar (if using), and salt.
Add warm water and whisk until dissolved. Let sit for 5–10 minutes if using sugar, until foamy (optional but helps activate yeast).
Add flour and stir until a sticky dough forms. Adjust with small amounts of water or flour if needed.
Cover the bowl with foil, plastic wrap, or a towel and let the dough rise in a warm place for 2–3 hours, until doubled in size.
Place a Dutch oven (with lid) in the oven and preheat to 450°F (230°C). Let it heat for an additional 15–20 minutes once preheated.
Transfer the dough onto a large piece of parchment paper. Lightly flour and shape into a round loaf. Score the top if desired.
Carefully remove the hot Dutch oven, place the dough (with parchment) inside, and cover with the lid.
Bake for 20 minutes covered, then remove the lid and bake for another 5–10 minutes until golden brown.
Remove bread and let cool on a wire rack for at least 20 minutes before slicing.