French Onion Recipe

Prepare onions

Slice onions thinly and separate into rings/strips so they cook evenly.

In a large heavy-bottomed pot or Dutch oven, melt butter with olive oil over medium heat until shimmering.

Add the sliced onions, stir to coat, then season with 1 tsp sea salt and 1 tsp freshly ground black pepper. Cook, stirring frequently, until onions begin to soften, about 10 minutes.

Sprinkle 1 tsp granulated sugar over the onions to encourage caramelization and continue cooking over medium-low heat. Stir every 5–7 minutes and scrape the browned fond from the bottom of the pot. Total caramelization time should be 35–45 minutes until onions turn deep golden-brown and very soft. Adjust heat as needed to prevent burning.

When onions are richly browned, sprinkle 1 tablespoon all-purpose flour over them and cook, stirring, for 1–2 minutes to remove raw flour taste; this will slightly thicken the soup.

Deglaze the pot with 1 cup dry white wine or dry sherry, scraping up any browned bits. Bring to a simmer and reduce by about half, 2–4 minutes.

Add 6 cups beef stock, 1 bay leaf, 3 thyme sprigs, 1 tsp Worcestershire sauce and 1 tsp sherry or red wine vinegar. Bring to a gentle simmer, then reduce heat and simmer uncovered for 20–25 minutes to allow flavors to meld. Taste and adjust seasoning with salt and pepper as needed. Remove bay leaf and thyme sprigs before serving.

Preheat oven to 425°F (220°C) with rack in upper third if you plan to broil for gratin.

Arrange focaccia slices on a baking sheet in a single layer. Brush both sides lightly with 2 tablespoons extra-virgin olive oil. If desired, rub the top of each toasted slice with the cut side of the halved garlic clove for a hint of garlic flavor.

Toast slices in the preheated oven 6–8 minutes, flipping once, until edges are lightly golden and crisp. Alternatively, grill or pan-toast them. Remove and set aside.

Divide finished soup among ovenproof bowls or crocks, leaving 1/2 inch headspace. Place 1–2 focaccia slices on top of each bowl or serve crostini on the side.

Ladle a thin layer of hot soup (or place bowls under broiler) so the surface is ready to receive cheese. Mound about 1/4 cup grated Gruyère per bowl (or enough to cover the bread) over the focaccia or directly onto the soup surface. Sprinkle a little grated Parmesan on top if using.

Place bowls on a baking sheet and put under the broiler (or in a 425°F oven) until cheese is melted, bubbling, and lightly browned, 2–4 minutes. Watch carefully to avoid burning. Alternatively, bake at 425°F until cheese melts, about 6–8 minutes.

Remove from oven with care (bowls will be hot). Garnish with a pinch of fresh thyme leaves and chopped chives if desired.