Onion Soup Recipe

Prepare broth

In a 4–5 quart pot, combine 6 cups chicken broth and 1 cup water. Add 1 bay leaf, 1 tablespoon soy sauce, and the thyme sprigs (or dried thyme). Bring to a gentle simmer over medium heat, then reduce heat to low to keep warm while you prepare the aromatics.

If using white wine, add it after onions and mushrooms are partially cooked (see Aromatics & Vegetables step). Adjust seasoning later with salt and pepper.

Caramelize onions

Heat 1 tablespoon olive oil and 2 tablespoons unsalted butter in a large skillet or sauté pan over medium heat until butter foams. Add the thinly sliced onions, 1 teaspoon granulated sugar, and 1/2 teaspoon of the sea salt. Stir to coat, then cook, stirring occasionally, for 15–20 minutes until the onions are softened and golden-brown at the edges (longer for deeper caramelization). Lower the heat if they begin to burn.

Cook mushrooms and garlic

Push the onions to one side of the pan (or remove briefly to a bowl). Add the sliced mushrooms to the pan and cook over medium-high heat for 5–7 minutes until they release liquid and begin to brown. Add the minced garlic and cook 30–60 seconds until fragrant. Recombine onions and mushrooms, taste and add remaining 1/2 teaspoon sea salt if needed.

Deglaze (optional)

If using the 1/2 cup white wine, pour it into the pan to deglaze, scraping any browned bits from the bottom. Cook until the liquid has mostly evaporated, about 2–3 minutes. Transfer the onion–mushroom mixture into the warm broth pot.

Simmer

With the onion–mushroom mixture in the warm broth, bring the soup to a gentle simmer. Simmer uncovered for 10–12 minutes to allow flavors to meld. Taste and adjust seasoning with up to 1/2 teaspoon additional salt and the 1 teaspoon black pepper as needed.

Finish and serve

Remove and discard thyme sprigs and bay leaf. Stir in 1 teaspoon fresh lemon juice (optional) to brighten the flavors. Ladle soup into bowls and garnish each serving with sliced green scallions and a sprinkle of chopped fresh parsley.