- 3 tablespoons unsalted butter, cut into pieces (olive oil for vegan)
- 4 lbs yellow onions, halved and sliced vertically into 1/4-inch-thick slices
- 2 cups water, plus extra for deglazing
- 1/2 cup dry sherry
- 6 cups low-sodium vegetable broth
- 6 sprigs fresh thyme
- 1 bay leaf
- Salt and freshly ground black pepper
- 1 small baguette, cut into 1-inch slices (best if a few days old, so it’s crusty)
- 4 – 6 slices of Swiss cheese (sliced thickly)
- Preheat oven to 400F.
- Coat the inside of a large cast iron Dutch oven or heavy bottomed pot with non-stick spray. Add butter, onions, and 1 tsp salt and cook, covered, for 1 hour.
- Remove the pot from the oven, stir the onions, and cook, mostly covered but with the lid slightly ajar, another hour.
- Stir again, scraping the sides of the pot, and continue cooking another 30-45 minutes until the onions are very soft and golden brown.
- Move the Dutch oven to the stovetop and set on medium-high heat. Cook, uncovered and stirring regularly, until the liquid evaporates, the onions turn a darker brown, and a dark crust begins to form on the bottom of the pot, about 20-25 minutes.
- Deglaze with 1/4 cup water. Scrape the bottom of the pot to remove the fond.
- Continue cooking until another dark crust has formed. Continue to deglaze with water 3 more times until the onions are very dark brown.
- Deglaze a final time with the sherry and cook, stirring, until the liquid evaporates, about 5 more minutes.
- Add 2 cups water, the broth, thyme, bay leaf, and additional 1/2 tsp salt. Increase heat to high and bring to a simmer, scraping any remaining fond from the bottom and sides of the pot.
- Reduce heat to low and simmer, covered, another 30 minutes.
- Remove the thyme and bay leaf and adjust seasoning to taste.
- Meanwhile, toast the baguette slices in a toaster oven or 400 degree oven (or … if the bread was a few days old, skip this step).
- When ready to serve, top a bowl of soup with two slices of bread, a slice or two of Swiss, and place under the broiler until the cheese is melted and beginning to brown, about 5 minutes.
Freeze left-overs for later in individual portions, without cheese. Then thaw, reheat, and when almost ready, put cheese on the top and broil for a few minutes to melt/brown the cheese. This was a great recipe!! Made about 8 individual servings.