Ingredients: (Serves 4)
4 pounds of yellow onions (about 4 large or 8 small onions) peeled and finely sliced lengthwise (not diced)
3 quarts of beef stock
one french baguette, or sourdough, if you prefer (stale bread works too)
8 thick slices of Gruyere or Emmentaler cheese
2 tablespoons of butter
2 tablespoons of olive oil
1 teaspoon sherry wine vinegar or white wine vinegar
1 tablespoon flour
(Place these on a square of cheesecloth and tie with cooking twine into a bundle. See the slideshow for images of how my daughter did this, above).
8-10 black peppercorns
2 bay leaves
4 sprigs of thyme
2 sprigs of sage optional
In a large stock pot, warm and melt the butter with the olive oil over medium heat. Add the onions and 2 teaspoons of salt and stir often over low heat for about 1.5 to 2 hours, until they have cooked down to a dark brown caramelized mush. (See photos in slideshow above). As you cook them, be sure to scrape the sides of the pan so that it doesn't burn, and to keep the heat on low.
Add the flour, turn heat up to medium, and cook stirring another couple of minutes.
Add the beef stock and the sachet, and bring to a simmer.
Cook, simmering for about 30-45 minutes, until the stock has reduced and the flavor is rich and deep.
Meanwhile, preheat your oven to 300 degrees.
Slice your baguette (we like fairly thick slices but you can go thin if you prefer), place them on a lined baking sheet, drizzle with olive oil and season with salt and pepper, and toast these on both sides, flipping once after a few minutes and being careful not to burn any as I usually do.
To assemble soup and bring it all together, ladle in to oven-safe individual bowls, add toasted baguettes slices (see images above), and top with cheese slices. (We prefer Gruyere cheese, though some may find this a bit strong. Traditionally, most people use Swiss Emmentaler.)
Place bowls on a lined baking sheet to catch any dripping soup or cheese, and slide under the broiler for just a couple of minutes until the cheese topping is fully melted and bubbling, but again, be very careful not to burn it during this step.
Because after all these hours of work, it would be a shame to make the soup, but not get to eat it, too.
A large mixed green salad, with apple or pear slices, some dried cranberries and crunchy nuts and a sherry or white wine vinegar dressing, pairs really nicely with this hearty, rich dish, and adds some crunch and acidity to cut through the heaviness of the cheese, we find.