Why It Works
- Low-protein all-purpose flour allows for plenty of buttermilk without excessive gluten formation, so the bread is chewy but tender—never tough.
- An extra 1/8 teaspoon baking soda is the most reliable way to mimic the casual, rounded teaspoon measurements more common in days of yore, ensuring that the buttermilk's acidity is fully spent, for a fluffy loaf with a subtle pretzel-like flavor.
- Sifting improves distribution of the soda while aerating the flour, making it easier to incorporate the buttermilk without any lumps.
- Buttermilk has the perfect viscosity and pH for this recipe, so steer clear of DIY alternatives (and trust me, I've tried them all).
Once upon a time, soda bread was baked over hot coals in a covered skillet, trapping steam from the dough to produce a wonderfully crusty loaf of bread—a setup anyone can re-create in a Dutch oven. Teamed up with low-protein all-purpose flour and volatile baking soda, buttermilk hits the sweet spot of gluten and carbon dioxide formation, creating a moist and fluffy loaf of soda bread that's chewy and crusty all at once.
15 ounces all-purpose flour, such as Gold Medal (3 cups; 425g)
1 3/4 teaspoons (7g) Diamond Crystal kosher salt; for table salt, use the same weight or half as much by volume
1 1/8 teaspoons (6g) baking soda (see note)
18 ounces low-fat cultured buttermilk (2 1/4 cups; 510g), well shaken
Adjust oven rack to middle position and preheat to 450°F (230°C) at least 15 minutes in advance. Roughly cover the bottom of a deep 10-inch cast iron or enameled Dutch oven with a sheet of parchment paper; no need to trim.
Combine flour, salt, and baking soda in a large bowl and whisk a full minute to combine. Stir in buttermilk with a flexible spatula until dough is fully moistened and no pockets of flour remain. For extra-fluffy results, stop folding as soon as dough comes together. For extra-chewy results, fold dough about 20 seconds more. Scrape sticky dough into prepared Dutch oven and smooth with a spatula into a rough boule-like shape. Score deeply into quarters with a sharp knife or razor, cleaning the blade between each slice.
Cover and bake until well risen and golden, 45 minutes. Remove lid and continue baking until chestnut brown, with an internal temperature of 210°F (99°C), 12 to 15 minutes longer. Invert onto a wire rack, discard parchment, turn right side up, and cool until crumb has set, about 30 minutes. Cut thick slices to accompany hearty soups and stews, or slice thinly for sandwiches. (This will be easier if bread is allowed to cool 2 hours more.) Store up to 24 hours in an airtight container and toast to freshen bread before serving.
For extra-fluffy bread with a craggy crust and a coarse, open grain (perfect for soaking up stews and sauces), handle the dough as briefly as possible. For an extra-chewy loaf with a glossy crust and a fine, even crumb (great for thinly sliced sandwich bread), stir and fold the dough about 20 seconds more.
Unless your digital scale is exquisitely sensitive, measure the baking soda by volume; even an extra gram can produce an unpleasantly soapy loaf of bread.