Baking Adventures: Sourdough Purple Sweet Potato Yogurt Beet Juice Bread

Okinawan sweet potato sourdough bread.

This is my 3rd sourdough loaf using my own homegrown starter (which is 2 weeks old). I'm hoping to strengthen the sourness over time, but so far I'm quite happy with the results.

 Here is the method I used for this loaf:

360g all purpose flour
40g whole wheat flour
300g spring water
8g sea salt
130g (~½ cup) mashed steamed Okinawan sweet potatoes
130g (~½ cup) Greek yogurt
2T beet juice, stirred into the yogurt
⅓ cup walnuts
80g sourdough starter, at peak, 100% hydration
79% hydration
Autolyse 1 hour
6 hours bulk fermentation at room temp
Stretch and fold at 30 minute intervals for 1st 2 hours
Preshape, bench rest 30 minutes
Envelope fold, shape, place seam side up in linen-lined, floured bowl
Rest at room temp 1.5 hours
Proof in refrigerator 16 hours
Bake 400°F 40 minutes
Lid off, 20 more minutes