Budget Sourdough Discard Roasted Root Vegetable and Thyme Biscotti

Name: Budget Sourdough Discard Roasted Root Vegetable and Thyme Biscotti
Prep time: 25 min
Cook time: 50 min
Total time: 1 h 15 min
Yield: 12 servings
Cuisine: Contemporary
Ingredients: 1 cup (240 ml) active sourdough starter discard, at room temperature; 1¾ cups (220 g) all-purpose flour; 3 tablespoons (45 ml) olive oil; ¾ teaspoon (4 g) sea salt; ¼ teaspoon (1.3 ml) freshly ground black pepper; 2 whole (180 g) medium carrots, peeled, cut into ¼-inch (6 mm) half-moons; 2 whole (200 g) medium parsnips, peeled, cut into ¼-inch (6 mm) half-moons; 1½ tablespoons (22 ml) olive oil; ¼ teaspoon (1½ g) sea salt; 1½ tablespoons (4 g) fresh thyme sprigs, leaves removed from stems, finely chopped

From the MyKitchenBank Kitchen

Crispy, twice-baked sourdough biscotti studded with roasted carrots and parsnips, perfumed with fresh thyme. This savory biscotti transforms sourdough discard into an elegant side or snack, with a satisfying crunch that pairs beautifully with cheese, salads, or soup. Perfect for using up excess sourdough starter while creating a budget-friendly, zero-waste treat.

Prep: 25 min
Cook: 50 min
Wait: 15 min
Total: 1 hr 30 min
Makes: 24 biscotti pieces

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Steps

Before you start

Preheat oven to 425°F (220°C) about 30 minutes before you start (you'll use it for roasting vegetables first).
Have your sourdough discard at room temperature—it doesn't need to be freshly fed, just active.
Line two large baking sheets with parchment paper for the vegetable roasting and the biscotti baking.

1
Roast the root vegetablesOven 425°F / 220°C
- Toss the carrots and parsnips with 1.5 tablespoons (22 ml) olive oil and ¼ teaspoon (1.5 g) sea salt on a large baking sheet.
- Spread in a single layer.
- Roast in a preheated 425°F (220°C) oven for 20–25 minutes, stirring halfway through, until the edges are caramelized and tender.
- The vegetables should be soft inside with golden, crispy edges.
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Ready when: Carrots and parsnips are golden-brown at the edges and very tender when pierced with a fork
Tip: Cut the vegetables evenly so they roast at the same rate; thinner slices will crisp up nicely inside the biscotti.
2
Cool and chop roasted vegetables
- Remove the vegetables from the oven and spread them on a plate or cutting board to cool for about 5 minutes.
- Once cooled enough to handle, roughly chop them into ½-inch (1 cm) pieces.
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Ready when: Vegetables are cool enough to touch and chop without burning yourself
Tip: Don't chop too small—chunky pieces will create pleasant texture bursts in the biscotti.
3
Mix the dough
- In a medium bowl, combine 1 cup (240 ml) sourdough discard, 1.75 cups (220 g) all-purpose flour, 3 tablespoons (45 ml) olive oil, ¾ teaspoon (4 g) sea salt, ¼ teaspoon black pepper, and 1.5 tablespoons (4 g) chopped fresh thyme.
- Stir with a wooden spoon until a shaggy dough forms.
- Add the cooled chopped vegetables and fold them in gently until evenly distributed throughout.
- The dough should be slightly sticky but hold together.
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Ready when: Dough is shaggy, holds together, and vegetables are evenly distributed
Tip: Don't overmix—lumpy dough is fine. The dough will be softer than bread dough because of the sourdough discard moisture.
4
Shape the dough logOven 350°F / 175°C
- Reduce oven temperature to 350°F (175°C).
- Lightly oil a 9×4-inch (23×10 cm) loaf pan or line it with parchment.
- On a lightly oiled work surface, shape the dough into a log about 10 inches (25 cm) long, 3 inches (7.5 cm) wide, and 1.5 inches (4 cm) tall.
- Place it in the loaf pan or transfer it to a parchment-lined baking sheet.
- Smooth the top gently.
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Ready when: Dough is shaped into an even log with a smooth top
Tip: Oil your hands instead of flouring to prevent sticking and keep the dough tender.
5
Bake the dough logOven 350°F / 175°C
- Bake at 350°F (175°C) for 25–28 minutes until the top is lightly golden and a skewer inserted in the center comes out clean or with just a few moist crumbs.
- The log should feel firm and spring back when lightly pressed.
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Ready when: Top is golden-brown, and a skewer inserted in the center comes out clean or with just a few moist crumbs
Tip: Don't overbake at this stage—the log needs to be slightly underbaked so it doesn't dry out too much before slicing.
6
Cool and slice the log
- Remove the log from the oven and let it cool for 8–10 minutes on the pan.
- This makes slicing easier without the biscotti breaking apart.
- Using a serrated bread knife with a gentle sawing motion, slice the log on a slight diagonal into ½-inch (1 cm) thick pieces.
- You should get about 24 slices.
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Ready when: Log is cool enough to slice without falling apart, and cuts are clean
Tip: Use a serrated knife and a gentle sawing motion—don't press down hard or you'll crumble the log.
7
Second bake—arrange biscotti
- Stand each slice upright on a parchment-lined baking sheet, spacing them about ½ inch (1 cm) apart.
- They should look like little dominoes standing up, showing the vegetable-studded cross-section.
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Ready when: Slices are arranged upright with even spacing
Tip: Standing them upright exposes more surface area for crisping and creates that classic biscotti texture.
8
Final bake and crispOven 350°F / 175°C
- Bake the biscotti at 350°F (175°C) for 10–12 minutes until they are light golden and feel very firm when you tap them.
- They should sound slightly hollow.
- Let them cool on the pan for 2 minutes, then turn each piece onto its other flat side and bake for another 8–10 minutes until that side is also golden and crispy.
- The finished biscotti should be uniformly golden and crunch when you bite into them.
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Ready when: Biscotti are uniformly golden, sound hollow when tapped, and crunch easily when bent
Tip: Turn them halfway through the second bake to ensure even crisping on both flat sides. If they're still slightly soft, give them 2–3 more minutes.
9
Cool completely
- Transfer the biscotti to a wire rack or clean countertop to cool completely, about 15 minutes.
- As they cool, they will continue to firm up and become crunchier.
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Ready when: Biscotti are completely cool and sound crackly when bent
Tip: Cool them completely before storing—residual warmth can create steam and soften them.

Good to know

Tips

Sourdough discard is perfect for this recipe because its mild tang balances the sweetness of roasted root vegetables. Don't use overly active or recently fed starter—a dormant, slightly thickened discard works best.
This recipe is excellent for zero-waste cooking: use vegetable scraps (carrot and parsnip ends) for stock, and the sourdough discard that would otherwise be discarded.
Serve these biscotti alongside cheese and pickles, dipped in soup, or as a savory-crunchy snack with a glass of wine. They pair wonderfully with soft cheeses like ricotta or goat cheese.
If your dough seems very wet after mixing in the vegetables, add 1–2 tablespoons more flour. Sourdough discard can vary in hydration depending on how it was maintained.

Storage & reheating

Store in an airtight container at room temperature for up to 2 weeks. Biscotti improve slightly as they sit—the flavors meld and they become even crunchier. You can also freeze them in a freezer bag for up to 3 months; thaw at room temperature for 30 minutes. To reheat, warm gently in a 300°F (150°C) oven for 3–5 minutes to restore crispness.

Substitutions

medium parsnips → sweet potato or rutabaga, cut into the same size. Parsnips have a mild, slightly sweet flavor; these alternatives will shift the taste profile but still work beautifully. Sweet potato adds sweetness; rutabaga is more earthy.
fresh thyme sprigs → dried thyme (use 0.5 tablespoon / 1.5 g) or fresh rosemary. Dried thyme is concentrated, so use less. Rosemary will be more assertive; chop it finely.
olive oil → neutral oil such as vegetable, sunflower, or avocado oil. Neutral oils won't impart flavor; the biscotti will taste more purely of vegetables and sourdough.
all-purpose flour → whole wheat flour (use 1.5 cups / 180 g) or spelt flour. Whole wheat will make the biscotti denser and nuttier; reduce slightly to account for its higher absorption. Spelt is more delicate and will require careful handling.