Multigrain Bread

For the soaker: 

plus 1 tsp.) old-fashioned oats

plus 2 tsp.) sesame seeds

hulled sunflower seeds

plus 1 tsp.) flaxseeds

quinoa

cold water

For the dough: 

plus 3½ tbsp.) all-purpose flour

(¾ cup) whole wheat flour

plus 2 tbsp.) rye flour

(Scant 1 tsp.) instant yeast

sourdough starter*

plus 5 tbsp.) water at 75° F

fine sea salt

egg white mixed with 1 tbsp. water, for brushing