1 1/2 teaspoons instant yeast
1 1/2 teaspoons salt
1 1/2 teaspoons sugar
2 1/2 cups King Arthur Unbleached All-Purpose Flour
2 cups ripe (fed) sourdough starter
1/2 cup lukewarm water
Combine all the ingredients and mix and knead — by hand, mixer, or bread machine — to make a soft, smooth dough; about 15 to 20 minutes by hand, 7 to 10 minutes in a mixer, and 20 to 30 minutes in a bread machine.
Place the dough in a lightly greased bowl and let it rise for 45 to 60 minutes, until puffy but not necessarily doubled in bulk.
Lightly grease a 9” x 5” loaf pan.
On a lightly greased work surface, gently deflate the dough, and form it into a 9” log. Place the log in the prepared pan, cover, and let it rise for 60 to 90 minutes, until it crests about 1” over the rim of the pan.
Preheat the oven to 350°F.
Bake the bread for 40 to 50 minutes, until it’s light gold and a digital thermometer inserted into the center reads 190°F.
Remove the bread from the oven, and after a couple of minutes turn it out of the pan onto a rack to cool. Store, well-wrapped, at room temperature for several days; freeze for longer storage.