Sourdough Discard Tempura Batter

A whisper-light, bubbly batter that clings gently and crisps dramatically — the perfect discard-based coating for vegetables, seafood, or seasonal herbs.

At a Glance

• Loaf Style: Batter (fried)

• Skill Level: Intermediate

• Total Time: ~30 minutes

• Prep Time: ~10 minutes

• Yield: Enough for ~3–4 servings

• Hydration: N/A

• Cook Temp: 350°F / 175°C (frying)

• Baking Vessel: Heavy-bottomed pot or deep fryer

Ingredients

• 100g sourdough discard (unfed)

• 60g ice-cold sparkling water (or just-cold water)

• 30g all-purpose flour

• 30g rice flour (for extra crispness)

• 1 tsp cornstarch

• ¼ tsp fine sea salt

• Neutral oil, for frying

• Assorted veggies or seafood (e.g. sweet potato, zucchini, green beans, prawns, shiso leaves)

Instructions

Make the Batter
1. In a medium bowl, whisk together sourdough discard, cold sparkling water, and salt.
2. Add flour, rice flour, and cornstarch. Stir gently — lumps are okay! Overmixing will reduce crispness.
3. Place the bowl over another bowl filled with ice to keep it cold while frying.

Heat the Oil
4. Heat oil in a heavy-bottomed pot to 350°F / 175°C. Line a tray with paper towel and set a wire rack nearby.

Fry in Batches
5. Pat your chosen vegetables or seafood dry. Dip into the batter, letting excess drip off.
6. Gently lower into the hot oil. Fry in small batches for 2–4 minutes, flipping once, until golden and crisp.
7. Transfer to the rack to drain. Sprinkle with flaky salt while still hot.

Serve Immediately
8. Best enjoyed right away with a dipping sauce like tempura tentsuyu, ponzu, or spicy mayo.

Visual Cues

• Batter should puff slightly and fry to a pale, lacy crisp with golden edges.

• Texture should be thin and crunchy, not bready or heavy.

Why This Works

The natural acidity of the discard slows gluten development and reacts with cold water for lightness. Rice flour and cornstarch promote crispness, while cold temperature and minimal mixing ensure delicate, airy bubbles that fry up golden.