French Onion Sourdough Loaf

There’s nothing quite like the aroma of freshly baked sourdough bread—but when you infuse it with deeply caramelized onions and the rich, savory flavors of classic French onion soup, it becomes something truly special. This French Onion Sourdough Loaf is a heartwarming fusion of rustic sourdough and the soulful comfort of onions slowly cooked until golden.

This recipe takes a bit of patience, but the results are more than worth it. With each slice, you’ll enjoy a chewy crust, a soft, airy crumb, and pockets of sweet caramelized onion that melt in your mouth. Perfect with butter, soup, or cheese, it’s a show-stopper for any bread lover.

Whether you’re a seasoned sourdough baker or just starting out, this recipe is approachable and flexible. You can prep the onions ahead, and let the dough ferment overnight, letting time (and nature) do most of the work. Let’s get into the details!

🕒 Cooking Time and Serving

• Prep Time: 30 minutes (plus 6–12 hours bulk fermentation)

• Cook Time: 45 minutes

• Total Time: ~8–14 hours (mostly inactive)

• Servings: 10–12 slices

• Loaf Size: One standard round or batard loaf

🧾 Ingredients

For the Caramelized Onions:

• 2 large yellow onions, thinly sliced

• 1 tbsp olive oil

• 1 tbsp unsalted butter

• 1 tsp salt

• ½ tsp sugar (optional, for faster caramelization)

• 1 tsp balsamic vinegar (optional, for depth)

For the Sourdough Bread:

• 500g bread flour

• 350g water (room temperature)

• 100g active sourdough starter (100% hydration)

• 10g fine sea salt

• All caramelized onions (cooled)

👩‍🍳 How to Make French Onion Sourdough Loaf

Step 1: Caramelize the Onions

1. In a large skillet, heat olive oil and butter over medium-low heat.

2. Add sliced onions, salt, and optional sugar.

3. Stir occasionally for 30–40 minutes until deeply golden and soft. Deglaze with balsamic if using.

4. Let onions cool completely before adding to dough.

Step 2: Mix the Dough

1. In a large bowl, mix flour and water until no dry bits remain (autolyse). Let rest for 30–45 minutes.

2. Add sourdough starter and mix until fully incorporated.

3. Add salt and mix again.

4. Gently fold in the cooled caramelized onions until evenly distributed.

Step 3: Bulk Fermentation

1. Cover the bowl and let it ferment at room temperature (around 70–75°F or 21–24°C) for 4–6 hours.

2. Perform 3–4 stretch and folds every 30 minutes during the first 2 hours to build strength.

Step 4: Shape and Proof

1. Lightly flour your surface. Turn out the dough, pre-shape, and let rest for 20 minutes.

2. Shape into a round or batard loaf. Transfer to a floured proofing basket.

3. Cover and refrigerate overnight (8–12 hours) for a cold retard.

Step 5: Bake

1. Preheat oven to 475°F (245°C) with Dutch oven inside.

2. Turn the dough out onto parchment paper. Score the top with a sharp blade.

3. Transfer to hot Dutch oven, cover, and bake for 20 minutes.

4. Remove lid and bake for another 20–25 minutes, until golden brown and crusty.

5. Let cool at least 1 hour before slicing.

📝 Notes

• Onion Flavor: Make sure the onions are fully caramelized and cooled, or they’ll affect the dough’s structure.

• Starter Health: Use a bubbly, active starter for the best rise and flavor.

• Hydration Adjustment: Onions introduce moisture, so the dough may be slightly wetter. Add a little flour if too sticky.

• Add Cheese: For a cheesy variation, fold in 50g shredded gruyère or sharp cheddar with the onions.

❓ FAQs

Q: Can I use all-purpose flour instead of bread flour?
A: Yes, but the loaf may be slightly less chewy. Consider reducing the hydration slightly.

Q: Can I skip the cold retard?
A: Yes, but the flavor and crust benefit greatly from the overnight fridge proof.

Q: Can I use dried onions instead?
A: Not recommended. Fresh, slow-cooked onions give the best flavor and texture.

Q: Can I freeze the loaf?
A: Absolutely! Slice it first for easy reheating. Freeze up to 2 months.

🔢 Nutrition (Per Serving – Approx. 1 Slice)

Note: Values are estimates based on 12 slices per loaf.

⚠️ Disclaimer

Enjoy homemade sourdough in moderation as part of a balanced diet. This recipe contains gluten and may include dairy (from butter) and sulfites (from balsamic vinegar). Always check ingredient labels for allergens, and consult a healthcare provider for specific dietary concerns.