Combine ingredients in a small bowl and mix well. Cover with plastic wrap and let sit out at room temp for 12-24 hours before using. If longer than 24 hours, place in the fridge for up to 3 days and remove from fridge for 2 hours before using.
For the biga:
Combine ingredients in a bowl and using wet hands form until a mass. Knead for 2 minutes, wetting hands as necessary to keep dough from sticking too much to hand. Let dough rest for 5 minutes. Knead again for 1-2 minutes with wet hands. Cover with plastic wrap and place into the fridge for at least 8 hours, up to 3 days. Remove from the fridge 2 hours before making the final dough.
For the final dough:
Break up the soaker and the warmed biga into pieces and place in the stand mixer with the dough hook. Add the rest of the ingredients, including the seeds. Knead with the dough hook for 4-5 minutes until the dough becomes cohesive. Adjust the flour/water to get a dough that is smooth and supple and not dry. Continue to knead the dough until it becomes a smooth mass and passes the windowpane test. Shape into a ball and place in a greased bowl or a dough rising bucket and cover with lid or plastic wrap.
Allow the dough to rise for 45-60 minutes until it is 1 1/2 times its original size. Transfer to a lightly floured work surface and shape into a loaf or a batard shape. Place in a greased loaf pan for a loaf, and on a parchment lined baking sheet for a batard. If baking a batard, prepare the oven for steam baking by placing a pizza steel and steam pan in the oven to preheat at 425. Cover dough with greased plastic wrap and allow to rise for another 45-60 until 1 1/2 times original loaf size.
Score the bread and place into the oven. If baking batard, pour 1 cup of water into the steam pan. Reduce oven temp to 375, and bake for 15 minutes. Rotate 180 degrees and bake for another 15-25 minutes until loaf is golden brown and sounds hollow when thumped. It should register 200 degrees internally with an instant read thermometer. Transfer to cooling rack to cool.