French Onion Soup with Bone Marrow

Ingredients

• 6 large Yellow Onion (peeled and thinly sliced)
• 4 tablespoons Unsalted Butter (room temperature, cut into pieces)
• 2 tablespoons All-Purpose Flour (sifted)
• 2 teaspoons Tomato Paste (optional, adds depth)
• 6 cups Beef Bone Broth (low‑sodium)
• 0.25 cup Cabernet Sauvignon (optional, adds richness)
• 2 tablespoons Brandy (optional, apple brandy works well)
• 1 tablespoon Fish Sauce (adds umami)
• 2 tablespoons Worcestershire Sauce (adds depth)
• 2 tablespoons Soy Sauce (adds salt and umami)
• 1 teaspoon Marmite (optional, strong umami)
• 4 sprigs Fresh Thyme (for bouquet garni)
• 4 sprigs Fresh Parsley (for bouquet garni)
• 1 leaf Bay Leaf (for bouquet garni)
• 2 large leaves Leek Leaves (wrap bouquet garni)
• 1 cup Gruyère Cheese (shredded, for topping)
• 0.5 cup Parmesan Cheese (freshly grated, for topping)
• 1 large Baguette (cut into 2 cm thick slices)
• 2 bones Bone Marrow Bones (large marrow bones, thawed)
• 1 clove Garlic (finely grated)
• to taste Salt (sea salt)
• to taste Black Pepper (freshly ground)

Instructions

1. Prepare and roast bone marrow bones

   Season the thawed marrow bones with a light brine, wrap each bone in crumpled aluminum foil to catch the fat, and place on a baking sheet. Roast in a pre‑heated 400°F oven for about 20 minutes until the marrow is puffed and the fat has rendered.

   Time: PT30M

   Temperature: 400°F

2. Slice the onions

   Trim the root ends, halve each onion, peel off the outer skin, then thinly slice all onions on a cutting board using a sharp chef’s knife.

   Time: PT15M

3. Prepare baguette slices

   Trim the baguette and cut into 2 cm thick slices. Set aside for toasting later.

   Time: PT5M

4. Render marrow fat and toast bread

   Remove the roasted bones, let cool slightly, then scoop out the rendered fat. Brush each baguette slice generously with the fat and place on a rack in the oven (convection if available) for 4 minutes until golden and crisp.

   Time: PT8M

   Temperature: 400°F

5. Grate cheeses

   Shred Gruyère and grate Parmesan; set aside for topping.

   Time: PT5M

6. Caramelize onions

   Melt butter in a 12‑inch sauté pan over medium heat, add all sliced onions, a splash of water, cover, and steam for 5 minutes. Uncover and continue cooking, stirring occasionally, until the onions reduce to a deep golden jammy color (about 45 minutes).

   Time: PT45M

   Temperature: medium heat

7. Make roux and add tomato paste

   Push the caramelized onions to the side, melt an additional tablespoon of butter, sprinkle flour, and stir for 2 minutes until lightly golden. Stir in tomato paste and cook another minute.

   Time: PT4M

   Temperature: medium heat

8. Deglaze and simmer the soup

   Add brandy (or skip if omitted) to deglaze, then pour in the Cabernet Sauvignon, followed by the beef broth. Bring to a gentle simmer and cook for 30 minutes, allowing flavors to meld.

   Time: PT30M

   Temperature: simmer

9. Add umami boosters and bouquet garni

   Stir in fish sauce, Worcestershire sauce, soy sauce, optional Marmite, and the wrapped bouquet garni. Simmer an additional 10 minutes. Remove the bouquet garni before serving.

   Time: PT10M

   Temperature: simmer

10. Assemble and broil

    Ladle hot soup into oven‑safe bowls, place a toasted baguette slice on top, spread a spoonful of softened bone marrow on the bread, heap shredded Gruyère and a sprinkle of Parmesan, then broil on high until the cheese bubbles and browns (about 5 minutes).

    Time: PT5M

    Temperature: broil

11. Garnish and serve

    Remove from oven, discard any remaining herbs, garnish with freshly chopped chives, and serve immediately while hot.

    Time: PT2M

Nutrition Facts

Calories

450

Protein

20g

Carbohydrates

30g

Fat

25g

Fiber

3g