French Onion Bouillon Recipe

Prepare onions

Peel and thinly slice the yellow onions and shallots. Aim for uniformly thin slices so they caramelize evenly (about 1/8 inch thick).

In a large heavy-bottomed pot or Dutch oven, melt the butter with the neutral oil over medium heat. The oil raises the butter’s smoke point and helps prevent burning while caramelizing.

Add the sliced onions and shallots to the pot and stir to coat with butter and oil. Spread them into an even layer and cook, stirring every 3–5 minutes, adjusting heat as needed to maintain a steady gentle sizzle. After 10 minutes, sprinkle the sugar and freshly ground black pepper over the onions; the sugar encourages even caramelization.

Continue to cook the onions low and slow for 35–50 minutes, stirring more frequently as they begin to brown (every 2–3 minutes) to prevent scorching. If the pot begins to look dry or the onions stick, add one to two tablespoons of water to deglaze. The onions should be deeply golden to mahogany in color and very soft when finished.

Once the onions are deeply caramelized, increase heat to medium-high and add the dry white wine. Scrape the bottom of the pot with a wooden spoon to deglaze and lift any browned bits (fond). Let the wine reduce by about half, 2–3 minutes.

Add the beef stock and water to the pot, stirring to combine. Add the bay leaves, fresh thyme sprigs, and black peppercorns.

Bring the mixture to a gentle simmer, then reduce heat to low and simmer uncovered for 25–30 minutes to allow flavors to meld and the broth to concentrate. Taste and season with kosher salt, starting with the indicated amount and adjusting to your preference.

If using, stir in the 2 tablespoons dry sherry or additional white wine at the end of simmering to brighten the flavor, then simmer 1 minute more. Remove and discard the bay leaves, thyme sprigs, and peppercorns (or strain the broth for a clear presentation).

If you prefer a smooth, clear bouillon: strain the broth through a fine-mesh sieve or chinois into a clean pot, pressing gently on solids to extract flavor but not cloud the liquid. Return the strained broth to a gentle simmer to adjust seasoning.

To serve in a classic French onion style: ladle hot bouillon into bowls, float a toasted baguette slice on each bowl, and sprinkle grated Gruyère over the toast. Place under a broiler or use a kitchen torch until the cheese is melted and bubbling (watch carefully to avoid burning).

Alternatively, ladle the clear bouillon into warmed cups, garnish with chopped fresh parsley and a crack of freshly ground black pepper. Serve immediately.