Sourdough Discard Irish Soda Bread

Ingredients

The Dough

The discard replaces some of the buttermilk and flour while adding its own acidity. You still need baking soda — the discard alone isn't enough leavening for a quick bread.

• 250g (2 cups) all-purpose flour
• 100g (¾ cup) whole wheat flour
• 150g (½ cup + 2 tbsp) sourdough discard (100% hydration, unfed)
• 165g (¾ cup) cold buttermilk
• 6g (1 tsp) baking soda
• 6g (1 tsp) fine sea salt

Optional Add-Ins

• 8g (1 tbsp) caraway seeds
• 80g (½ cup) raisins or currants

Total flour: 350g

Hydration: 75%

Pro tip: The discard adds real acidity to the mix — don't skip the baking soda thinking the sourdough will do the job alone. Quick breads need that instant chemical reaction. The discard's job here is flavor, not lift. Discard thickness varies. If your dough still feels stiff after mixing, add cold buttermilk one tablespoon at a time until it comes together into a shaggy, cohesive mass.

Equipment

Method

Mix the Dough (Discard first, then dry, then buttermilk)

Same principle as the classic version — minimum mixing, maximum speed. The only difference is the order: you'll incorporate the sourdough discard before adding the buttermilk so it blends evenly without overmixing.

1. Combine Dry Ingredients. In a large bowl, whisk together the all-purpose flour, whole wheat flour, baking soda, and salt. Add caraway or raisins here if using.
2. Add the Discard. Add the sourdough discard to the bowl. Use a fork to break it up and distribute it through the flour mixture. It'll look crumbly and messy — that's fine.
3. Add Buttermilk and Bring Together. Pour in the cold buttermilk and mix with a fork or your hand just until a rough dough comes together. It'll be sticky and shaggy — that's right. Don't smooth it out. If it's too dry, add buttermilk 1 tbsp at a time.

Tip: If your discard is cold from the fridge, that's fine — and actually preferred. Cold discard won't activate the baking soda prematurely.

Shape and Score (Same as the classic — rough is right)

Turn dough onto a lightly floured surface and shape into a round about 6 inches across. Score the cross deep — at least ½ inch, nearly to the edges.

1. Shape into a Round. Lightly flour your hands and surface. Turn the dough out and gently form it into a round ball, tucking edges underneath. Press to about 3 inches tall.
2. Score the Cross. Using a sharp knife or lame, cut a deep cross (½ inch deep) across the top, extending nearly to the edges. This is functional — it lets the bread expand and the center cook through.

Tip: Discard dough is slightly tackier than the classic version. Flour your hands, not the dough. If it sticks to the surface, use a bench scraper to lift it.

Bake the Loaf (Same timing as classic, slightly richer color)

The sourdough discard adds natural sugars from fermentation, which means this loaf browns a bit faster. Watch the color at the 35-minute mark.

1. Preheat to 425°F (220°C). Preheat oven with your Dutch oven or cast iron inside. Hot vessel = better bottom crust.
2. Transfer and Bake. Lower the loaf (on parchment) into the hot vessel. Bake at 425°F (220°C) for 20 minutes, then reduce to 400°F (205°C) for 18-22 more minutes. Watch the color — discard versions can go dark faster than the classic.
3. Check Doneness. Tap the bottom — hollow means done. Internal temperature should reach 195-200°F (90-93°C).

Tip: If it's browning too fast before 40 minutes total, tent it loosely with foil for the last 10 minutes.

Cool on a Wire Rack (30 minutes minimum)

Move to a wire rack immediately. The discard version has more moisture from fermentation — it needs the full 30 minutes to set the crumb.

1. Rest the Loaf. Place on wire rack and leave it alone for at least 30 minutes. The crumb is still finishing up.

Wait: PT30M

Shape the Loaf

Simple round — discard dough handles the same as the classic, just slightly stickier.

Traditional Round Boule (recommended)

1. Flour hands lightly. Keep flour on your hands, not the dough.
2. Form a round. Tuck edges underneath, press to about 3 inches tall.
3. Score deeply. Half-inch cross, edge to edge.

Proof test: No proof test — shape and bake immediately. The baking soda reaction has already started.

Bake

Two-stage bake for full crust development and a cooked-through interior.

Oven: 220°C / 425°F. Internal temperature when done: 90-93°C / 195-200°F.

Dutch Oven or Cast Iron Skillet (recommended)

Best option. Preheated vessel for a superior crust.

Equipment: Dutch oven or 10-inch cast iron skillet

1. Preheat vessel. Vessel goes in the oven while it preheats to 425°F (220°C).
2. Transfer and bake. 20 minutes at 425°F (220°C), then 18-22 minutes at 400°F (205°C).

Baking Sheet

Works fine. Use a preheated heavy sheet for better bottom browning.

Equipment: Parchment-lined baking sheet

1. Bake. 425°F (220°C) for 20 minutes, then 400°F (205°C) for 20-22 more minutes.

Note: Discard loaves go darker than the classic. Don't pull early based on color — tap the bottom to check.

Storage

• Room temperature: Best the day it's baked. Wrap in cloth or paper bag for up to 2 days. The discard adds slight moisture which helps it last a little longer than the classic.
• Refrigerated: Not recommended — refrigeration dries out quick breads.
• Frozen: Slice first, wrap tightly, freeze up to 4 weeks. Toast directly from frozen.
• Refresh: Toast slices or warm the whole loaf at 350°F (175°C) for 8-10 minutes.

Frequently Asked Questions

Can I use active (fed) starter instead of discard?

Yes, but the flavor will be milder since active starter is less acidic. It'll still work fine with the baking soda. If your starter is very recently fed and still sweet, consider using older discard if you have it — the extra acidity is what makes this version better than the plain classic.

My dough was much stickier than expected. Did I do something wrong?

The dough should be tacky and slightly sticky — that's normal. Handle it with floured hands and a bench scraper. Don't add more flour to compensate — a tacky dough bakes up more tender. However, the dough should not feel stiff or dry. If it does, add cold buttermilk one tablespoon at a time until it forms a shaggy, cohesive mass. Discard thickness varies, so adjust as needed.

How much discard can I use?

The ratio in this recipe (150g discard to 350g total flour) is the sweet spot. Go much higher and the dough gets too wet and the baking soda doesn't have enough buttermilk acid to fully activate. You can go as low as 100g discard if that's all you have — reduce buttermilk to 150g to compensate.

Does the age of the discard matter?

Yes, and it matters in a good way. Older discard (3-5 days in the fridge) is more acidic and gives you a tangier, more complex flavor. Fresh discard works but tastes closer to the plain classic. If you've been accumulating discard and it smells pleasantly sour, that's the stuff you want here.

Can I mix the dough ahead of time?

No. Once the baking soda hits the acid, the reaction starts immediately. You have a 10-15 minute window from mix to oven. Don't mix the dough, cover it, and come back to it. Shape it and get it in.

Is this noticeably different from the classic version?

Yes — the discard version has a more complex, slightly tangy flavor that's harder to place until someone tells you it's sourdough. The texture is very similar. Most people who try both prefer the discard version. It's the same work, better payoff.

Nutrition

Per serving (1 slice (1/10 loaf)): 180 calories, 36g carbohydrates, 6g protein, 1g fat, 2g fiber, 295mg sodium. Makes 10 servings.