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Steamed purple sweet potato turns the crumb a deep violet and keeps the loaf soft and moist for days. The potato brings extra moisture, so the dough uses less water than a plain loaf — it will still feel soft and slightly tacky. Look for purple sweet potatoes (often sold as Okinawan or Stokes purple) in larger supermarkets and Asian grocers.
Ingredients
- 450 g strong white bread flour
- 50 g wholemeal flour
- 200 g purple sweet potato, peeled, steamed and mashed, cooled
- 270 g water at about 26°C
- 100 g active sourdough starter, at its peak
- 10 g fine sea salt
Contains: wheat (gluten).
Method
- Steam the potato. Peel and chop the sweet potato, steam for 20–25 minutes until completely soft, then mash smoothly and leave to cool to room temperature. Weigh out 200 g.
- Mix. Whisk the starter into the water. Add both flours and the mashed potato and mix until there is no dry flour left. Cover and rest for 30 minutes.
- Add the salt. Sprinkle over the salt with a splash of water and squeeze it through the dough until it disappears.
- Stretch and fold. Over the next 2 hours, give the dough four sets of stretch and folds, 30 minutes apart.
- Bulk ferment. Cover and leave at 24–26°C until the dough has grown by 50–75%, is domed and has bubbles at the sides — usually 5–7 hours from mixing.
- Shape. Turn out, pre-shape into a round and rest 20 minutes. Shape into a tight boule or batard and place seam-up in a floured banneton.
- Cold prove. Cover and refrigerate for 12–16 hours.
- Bake. Heat the oven with a lidded cast-iron pot inside to 250°C for 45 minutes. Turn the loaf out, score, and bake covered for 20 minutes, then uncovered at 230°C for 20–25 minutes until deep brown and 96°C in the centre.
- Cool. Cool for at least 2 hours before slicing to see the purple crumb at its best.
Bake this with a live starter
Our San Francisco sourdough starter is a live culture held dormant rather than dehydrated — ready to bake with in about two hours.
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