6Tablespoonsto ¾ Cup water, lukewarm (I actually used 1 Cup)
Onion filling:
2onions, sliced
¼Cupolive oil
2Tablespoonssugar
2Tablespoonsbalsamic vinegar
3Tablespoonsfresh rosemary, minced
Instructions
For the filling (which is optional), add oil to a large skillet over medium high heat. Add onions and cook until they start to brown, about 10-15 minutes. Then stir in sugar until dissolved and add a splash of balsamic vinegar. Finally stir in herbs and cook for another minute or two. Let cool completely before adding to dough. You can make the filling a day in advance.
For the poolish starter, add ingredients to a large bowl and stir to combine. Let sit at room temperature for 3-4 hours to rise, then store in the fridge overnight.
Remove starter from fridge one hour before making dough.
Add flour, yeast, and salt to large bowl or a mixing bowl. Stir to combine, then add poolish and about 1/4 Cup water. Mix on low with a dough hook attachment or with a large spoon until dough comes together in a ball.
You might need to add more water as you mix. The dough should be really soft and sticky, but not slimy. If you’re using a mixer, it should stick to the bottom, but not the sides. If you’re mixing with your hands, dip a hand in water and use it to vigorously mix the dough until it reaches the right texture, probably 5-7 minutes.
Scrape dough onto a clean surface that’s been heavily coated with flour. Stretch dough out into a large rectangle. It should stretch really easily.
Add 1/2 of the onion filling to dough. Fold the dough into a book fold, folding left side to the center and right side over the left side. Rub the dough with a bit of olive oil, cover it, and let it rest for 30 minutes.
Stretch the dough out into another rectangle. It should easily stretch. Add the last 1/2 of the filling and do the same fold again. Rub with oil, cover, and let rise for 90 minutes. It might not double in size, but it will swell.
Cut dough in half with a serrated knife or a pastry cutter. Seal the edges so the filling doesn’t come out and shape each half into a long rectangle. My loaves were about 6 by 12 inches in size.
Set the loaves in a couche, which is just a floured towel that’s been bunched up so the loaves can’t touch each other.
Preheat oven to 500 degrees with baking stone in it for 25-30 minutes.
Flour a peel or the back of a baking sheet. Add a loaf of dough to the peel and slide it onto the hot stone.
Using a spray mist bottle, spray the sides of the oven with water creating steam. Repeat this process every minute or so 3-4 times. Then turn the oven down to 450 degrees and cook the bread for about 20 minutes until it’s a deep golden brown.
Remove loaf and cool on a rack for an hour before slicing.