This loaf combines the goodness of sourdough and whole grains with freshly shredded zucchini and honey. It is a lightly-sweetened version of a favorite summer treat.
In a medium bowl, mix sourdough starter, milk, and flours until combined into a stiff dough. Cover and soak 6-12 hours, or overnight.
Preheat oven to 400°F.
Place shredded zucchini in a clean towel and squeeze as much moisture out as you can.
In a small bowl, beat the eggs and whisk in honey, melted butter, and vanilla. Stir in zucchini shreds.
Sprinkle the baking powder, baking soda, salt, and cinnamon over the soured dough; add egg-honey mixture and mix in gently until well-combined. Fold in walnuts.
Divide the batter between two buttered loaf pans, filling each pan 1/2 to 2/3 full.
Place pans in the oven and bake for 40 minutes, or until the tops are set, the bottom has browned, and a knife inserted comes out clean.
