make the sponge:

1. In a small bowl, stir together the water and the sugar. Sprinkle the yeast overtop. Let stand five minutes or so until you see that the mixture is somewhat foamy. (This is an unnecessary step, but when you see that it’s foamy, you know that your yeast is active.) Stir in the 1/3 cup flour. Cover bowl with plastic wrap and let sit for 45 minutes or for as long as an hour and a half if time allows). The mixture should have at least doubled in bulk and look somewhat bubbly.
2. Meanwhile, toast the walnuts. Preheat the oven to 350ºF. Spread walnuts on a baking sheet and bake for about 10 minutes. This might take more or less time — keep an eye on them and set a timer. Nothing is worse than burning a sheetpan worth of nuts. Remove pan from oven and let nuts cool. Transfer walnuts to a clean tea towel and rub well to remove as much skin as possible. Transfer nuts to a colander or sieve and shake it over the sink to remove any excess skin. (Note: This skin removal process is an extra step, but I think it’s worth it because the skin can be so bitter.)make the dough:
3. Transfer this sponge to a large mixing bowl and stir in the water, 1 tablespoon of the walnut oil, flours and salt. Using a spoon or your hand, mix until the ingredients are well blended. Cover the bowl in plastic wrap and place in a warm spot to rise. (Note: If you need to create a warm spot, preheat your oven at a lowish setting for 1 minute — essentially, just turn your oven on for a minute and then turn it off. In other words, do not let the oven get up to 350ºF, for example, and then heat at 350ºF for that minute.) This initial rise can take anywhere from 2 to 4 hours. Be patient. One day my dough doubled in 2 hours; another day it took over 4. (Note: Now, I can’t say for sure because I haven’t tried this with this recipe, but I imagine (because I’ve had success with other recipes doing this) that you could place the dough in the fridge overnight at this point and let it rise slowly in the cool environment. If you need to go to work in the morning and the dough has risen considerably, just punch it down, cover it up, and place it back in the fridge.)
4. When the dough has doubled, punch it down using your hands or two forks or however you like to do this. Sprinkle the walnuts over top and gently knead them into the dough so that they are evenly dispersed. If your hand gets too sticky (which they likely will), dip them in water to make the kneading process a little easier. Once the walnuts have been added, drizzle the dough with the additional tablespoon of walnut oil and turn the dough to coat, adding a drizzling more of the walnut oil if necessary. (Notes: Adding flour at this point versus water to help with the sticking issue might be an instinct for many of you, but I shied away from adding flour after reading some of the notes in Tartine Bread. I think adding too much flour can affect the final flavor and texture of the bread, so I prefer to use water. This step is a little annoying, but just get through it quickly without worrying too much that the walnuts are completely evenly dispersed — they will be.)
5. OK, at this point, you will either divide the dough in half or leave it whole. If you have a large Dutch oven with straight sides, then just leave the loaf whole. Having made this several times now, this is my preference — I love the big boule it creates, even though removing it from my sloped-sided Dutch oven after it has finished baking is such a process. In some of the pictures here, you can see that I divided the dough in half and baked each separately in my sloped-sided Dutch oven, which made the removal process easy. If you divide the dough in half, place each half in a well greased bowl to complete this second rise. If you leave it whole, just leave the dough in the same mixing bowl you have been using. Place bowls in a warm draft-free spot.
6. Place a large Dutch oven with a lid or two Dutch ovens with lids in the oven and preheat the oven to 500ºF. If time allows, leave the Dutch oven in the oven for a whole hour. If not, 30 minutes is fine, too. When the loaves have nearly doubled (about an hour or less), remove the Dutch oven and lid from the oven being careful not to burn yourself. Remove the lid from its base and carefully plop the dough into the Dutch oven. Place the cover on top and return pot to the oven. Turn heat down to 450ºF. Bake for 20 minutes. Carefully remove top after 20 minutes and continue baking for an additional 20 to 25 minutes (if you have made one large loaf) or for 15 to 20 minutes (if you are baking smaller loaves). Once the loaves look nicely browned on top, turn them out onto a cooling rack. Let cool for as long as you are able to resist.