Onions: If the bay leaves are fresh, strip the leaves from either side of the vein. Throw the vein away and finely chop the leaves. Melt the butter in a sauté pan and add the fresh-chopped or whole dried bay leaves, as well as the onions. Sauté the onions until they just begin to brown. Add the milk, bring it to the boiling point and then turn it off. Let sit for ten minutes. Cool and strain, reserving the milk and onions separately. If using dried bay leaves, discard them.

Dough:Put the cooled milk in a bread bowl with the starter. Add the yeast, whole wheat flour, salt, and a cup of the bread flour. Stir in the onions and another cup and a quarter of flour, cover and let sit for ten minutes. If the dough is still sticky, stir in another quarter cup of flour.

Knead the dough on an oiled surface for ten seconds, return it to the bowl and cover. Let rest for ten minutes. Repeat the brief kneading for ten minutes more, return to the bowl, cover, and let rest for an hour.

Line a deep 8" bowl with a flour-rubbed dish towel, or generously flour a banneton.

Deflate and fold the dough over on itself, then shape it into a ball. Place it, seam-side up, in the prepared bowl or banneton. Cover and let rise until doubled, an hour and a half. Preheat the oven to 425°. If you have a baking stone, place it on a shelf in the bottom-third of the oven.

Invert the loaf onto a piece of parchment on the back of a baking sheet or peel. Spray the top with water, then slide it into the oven. Bake for 20 minutes then reduce the oven temperature to 375° and bake for another 30 minutes, until the center of the loaf registers 200°. Remove from the oven and cool on a rack.