Make the caramelized onions: Heat oil in a large skillet to medium heat on the stove top. Add onions and stir to coat with the oil. Cook, stirring every few minutes, until the onions soften and turn a golden brown. The entire process should take about 30 minutes. Salt the last few minutes of cooking. Once caramelized, remove onions from heat and set aside for 15 minutes to cool.

Add flour to a large mixing bowl. Dissolve the yeast in 1/3 cup warm water along with the salt; add to the flour and combine. Add the remaining water and onions and mix to combine. Cover the dough and let sit for an hour at room temperature to rise. The dough should be doubled in size.

Dust your work surface with flour and place dough onto work surface. Knead until the dough forms a loaf. Place in your loaf pan and let stand to rise again for 30 minutes.

Preheat your oven to 470 F. Place a small pot filled with water on the bottom rack of the oven to create steam. Bake dough for 15 minutes, remove water from the oven, reduce oven temperature to 450 F and bake for another 15 minutes. Remove bread from oven and let cool on a wire rack before serving.