It is possible to make croissant and viennoiserie using only natural sourdough, using dosage levels of up to 28% of total flour weight and eliminating the yeast from the mix. The recipe below will produce excellent croissants when using the overnight fermentation method detailed earlier in the book. But this process will take three days as the pastry is made as follows using the 3-4-3 system:
Day 1: Feed the starter, leave for 6 hours, then make the dough. Ferment for 2−3 hours, chill overnight @ 3℃.
Day 2: Make butter block, do a lock-in 3, then laminate with a 4-fold, followed by a 3-fold. Rest in the refrigerator for 40 minutes. Shape and wrap in plastic 20−22℃ for 5−6 hours, then place in the refrigerator overnight @3℃ (you may also use 5-4-3, or any other lamination system you want).
Day 3: Remove from refrigerator, egg wash and stand for 40 minutes to 1 hour. Proof until they jiggle. Please note that the final proof could take an additional 5−7 hours – this is not a product for the faint-hearted, due to the three days required to produce them! Bake the croissants in a fan oven @175℃−180℃ or a deck oven @ 200℃.
The full recipe and more tips are available in my book, The Art of Lamination: Advanced Technical Laminated Pastry Production.