300 ml buttermilk (about 1 1/4 cups), warmed to about 100°F
3 tablespoons unsalted butter, melted
2 tablespoons honey or sugar
2 1/4 teaspoons instant yeast
1 1/2 teaspoons salt
1/4 teaspoon baking soda
1 tablespoon butter, melted, for brushing the top
Directions
Gently warm the buttermilk to about 100°F. It may look a little curdled; that is fine. Stir in the melted butter and the honey or sugar.
In a large bowl, whisk the flour, yeast, salt, and baking soda. Pour in the buttermilk mixture and stir until a shaggy dough forms.
Knead by hand 8-10 minutes, or 6 minutes in a stand mixer with a dough hook, until smooth and elastic. The dough should be slightly tacky but not sticky.
First rise: place in a lightly greased bowl, cover, and let rise in a warm spot until doubled, about 60-90 minutes.
Shape: press the dough into a rectangle about 9 inches wide. Roll it up tightly from the short side, pinch the seam closed, and set it seam side down in a greased 9x5 loaf pan.
Second rise: cover and let rise until the dough crowns about 1 inch above the rim of the pan, 45-60 minutes. Preheat the oven to 350°F during the last 20 minutes.
Bake 35-40 minutes, until deep golden and the inside reads 190°F. Tent with foil after 20 minutes if the top browns too fast.
Turn out of the pan, brush the top with melted butter for a soft crust, and cool on a rack at least 1 hour before slicing.
Notes
Bread flour gives the best rise and structure. All-purpose works, but the loaf will be a bit softer and lower.
The baking soda tames the tang and helps browning. Leave it out if you like a more sour flavor.
No buttermilk: stir 1 tablespoon lemon juice or vinegar into regular milk and let it sit 5 minutes.
Keeps 3-4 days wrapped at room temperature, or freeze it sliced.