In a large bowl, mix the flour, sea salt, rosemary, and yeast together. Mix in the water and use a spatula to blend until well combined.
3 cups all-purpose flour, 1¾ tsp sea salt, ¾ cup fresh rosemary leaves, ½ tsp active dry yeast, 1½ cups water
Cover the bowl with plastic wrap or a clean, damp dish towel and allow it to sit on the counter overnight, at least 12 hours. (Patience is a virtue!)
Preheat oven to 450°F degrees with a Dutch oven inside.
Once preheated, carefully remove the Dutch oven from the hot oven and remove the lid from it. Use oven mitts!
Flour a clean work surface as well as your hands. Remove the dough from the bowl and form it into a ball. This is a no-knead recipe, but you may have to fold it a couple of times to get it to form the shape you want. Place the dough into the bottom of the Dutch Oven (be careful not to burn your hands; the cast iron will be HOT!)
Bake for 30 minutes with the lid on, then remove the lid and bake another 15-20 minutes, until the bread is golden brown.
The loaf should be nice and browned on top, and the crust should look crisp. If you gently tap on the bottom of the loaf with your finger, it should sound hollow. The proper internal temperature for baked bread is 195-210°F.
Remove from the oven and allow to cool. Cut and serve.