Soupe À L’oignon Recipe

Brown the shank

Pat the beef shank dry and season lightly with salt. Heat vegetable oil in a large heavy-bottomed pot over medium-high heat. Brown the shank on all sides, 6–8 minutes total, until deeply colored. Remove and set aside.

Sweat aromatics

Reduce heat to medium, add 1 tbs butter to the same pot and add the chopped carrot, celery and smashed garlic. Cook, stirring, until softened, about 4 minutes.

Build the broth

Stir in tomato paste and cook 1–2 minutes until slightly darkened. Deglaze with the white wine, scraping browned bits from the bottom. Return the shank to the pot and add beef stock (or water) to cover the shank by about 2 cm (1 inch). Add bay leaves, thyme sprigs, whole peppercorns and 1 tsp kosher salt.

Simmer

Bring to a gentle simmer, skim any foam, then reduce heat to low. Partially cover and simmer gently for 2.5–3 hours until meat is tender and falling from the bone and the broth is richly flavored.

Strain and reduce

Remove shank and set aside. Strain broth through a fine-mesh sieve into a clean pot, pressing solids to extract liquid. Discard solids. Taste broth and reduce over medium heat if necessary to concentrate flavor — aim for about 6–7 cups finished broth. Adjust seasoning with salt and pepper.

Caramelize onions

Melt 3 tbs butter with 1 tbs olive oil in a large wide skillet over medium-low heat. Add the very thinly sliced onions, 1 tsp kosher salt and 1 tsp sugar. Cook slowly, stirring every few minutes to prevent sticking, until deeply golden and jammy, 45–60 minutes. If onions brown too quickly, lower the heat. In the last 5 minutes, add 2 tbs sherry or wine (if using) and freshly ground black pepper and cook off alcohol.

Combine with broth

When onions are richly caramelized, add them to 6 cups of the strained beef broth (reserve extra broth for thinning). Bring to a gentle simmer and skim any excess fat. Reduce heat and taste; add the 2 tbs wine or madeira to finish the soup, and adjust seasoning with salt and pepper.

Prepare puff pastry

Preheat oven to 425°F (220°C). Line a baking sheet with parchment and lightly dust a work surface with flour. Unfold or roll each puff pastry sheet to even out seams.

Assemble cheese feuilleté

For each individual feuilleté (makes 4 rounds from 2 sheets), cut pastry into 4 equal squares or rounds (~10 cm/4 inches). Brush edges with beaten egg to help seal. Pile about 3/8 cup grated Gruyère + 2 tbs Emmental in the center of each pastry piece, leaving a 1 cm border. Sprinkle a little black pepper and optional thyme leaves over the cheese. Place a second pastry square on top and press edges to seal. Crimp with a fork or flute the edges. Brush tops with egg wash and score a shallow decorative pattern on each top to allow steam to escape.

Bake

Bake on the prepared sheet at 425°F (220°C) for 12–16 minutes, until puffed and deep golden. Rotate sheet halfway through for even color. Transfer to a rack and keep warm. Optionally, reheat briefly in a 350°F (175°C) oven until warmed through just before serving.

Shred some of the meat from the cooled beef shank and reserve a few small chunks for garnish. Stir the shredded meat into the caramelized onion-broth mixture and warm gently for 2–3 minutes to meld flavors.

Ladle 1.25–1.5 cups (300–360 ml) of soup into warmed bowls. Place one warm Alpine cheese feuilleté on top of each bowl or serve feuilleté on a small plate alongside if preferred (to keep pastry extra crisp). Garnish with chopped parsley and a turn of fresh black pepper. Serve immediately.