Smoked Sprouted Rye Bread with Walnuts

My fourth attempt of Smoked Sprouted Rye Bread from Chad Robertson's Tartine Book No.3 with increased leaven (30%). This time, instead of adding 100g smoked sprouted rye berries, I added 70g toasted walnut pieces and 60g smoked sprouted rye berries at the end of final mix. I changed the white flour ratio from 50% to 60% this time. 

It was a really cold day, so I used a handmade proof box for the bulk rise, so the environmental temperature was kept around 80-81F. The dough rose only 15-20%. 

For the final rise, I put the shaped loaf in the refrigerator (38F) for 10.5 hours, and left it at room temperature (72F) for 1.5 hours. 

Oven spring was pretty good, with nice open crumbs with large air holes. The proof box seemed to work well to develop the dough, and the long cold fermentation for final rise worked well, too. Both the texture and the flavor were the best among all the breads I ever baked, with the sweet and nutty complex flavors from the smoked sprouted rye berries and toasted walnuts. 

Also, I accidentally added a small amount of high-gluten flour to the dough and forgot to add wheat germ. I wonder if that affected the dough to create the better open crumbs this time. Anyway, I am very happy with the result (although it took a long time for the whole process due to the cold weather).