Sponge
1 1/2 c. Bread Flour
1/2 c. Whole wheat flour
1 c. Water
1/4 t. Instant yeast
Dough
3 c. bread flour
1 t. instant yeast
1 1/3c water (room temp)
2 t. table salt
Mix sponge in large mixer with dough hook, on low, until it makes a ragged, shaggy dough (2-3 minutes). Cover, and let sit overnight (or longer if refrigerated).
Add dough ingredients, except the salt, and mix with dough hook until it returns to a shaggy dough. Let rest for 20 minutes, covering
in situ, with plastic wrap. Add salt, and mix on low until the dough forms a loose ball, pulling away from the edges but still sticking to the bottom of the bowl. Increase mixing to medium for an additional minute or two until the dough forms a more cohesive ball.
Transfer the dough to a large, oiled bowl (3x the size of the dough), cover tightly with plastic wrap, and let rise in a warm, dark place for 75 minutes. Fold over, re-cover, and let rise twice more for 1 hour each.
Dust work surface and hands liberally with flour, and turn out dough onto surface. Work gently into a square, 9 inches to a side, and fold and roll into a loaf. (top corners in towards middle, then roll from point to base to form loaf. ) Place on parchment paper, dust with flour, and cover with plastic wrap for 30 minutes.
Turn oven on to 510 F. with a baking stone or large, heavy sheet pan in it. Let come fully up to temperature (30 minutes) while loaf continues to rise.
With VERY sharp knife or razor blade, slice top of loaf. (I like three or four diagonal cuts, my DW uses a single log slice.) Spray loaf with water and place into oven (still on parchment).
After 10 minutes, turn over down to 400 F. and rotate bread 180degrees. Bake for an additional 30-32 minutes longer. Remove and place on cooling rack. Don't slice for at least an hour, two is better.
Note: this is a very loose dough and quite sticky. That is normal. It doesn't make a tight, finely grained loaf (too much water for that), but it shouldn't have big holes either. And if it looks too flat when it's done, you had too much water.
In my cup: Oban 14 year.