09/10/2025
Lobster Thermidor recipe ,
Ingredients :
Lobsters
Two 1 1/2–pound (680 g) lobsters
One 1–pound (454 g) lobster (see notes)
For the Lobster Stock
2 tbsp (30 ml) vegetable or neutral oil
2 large shallots (about 8 oz / 225 g), thinly sliced
4 garlic cloves, smashed
1 celery rib (2 oz / 60 g), thinly sliced
Reserved lobster shells
1 tbsp (15 g) tomato paste
1/4 cup (60 g) brandy or dry sherry
4 cups (1 L) water
2 sprigs fresh tarragon
For the Lobster Thermidor
2 tbsp (30 g) unsalted butter
1 large shallot (4 oz / 113 g), finely minced
2 tbsp (16 g) all-purpose flour
1/4 tsp cayenne pepper
1 cup (237 g) Lobster Stock (from above)
1/2 cup (120 g) heavy cream
1 tbsp (15 g) Dijon mustard
2 oz (60 g) Gruyère cheese, grated or diced (plus more for topping)
1 tbsp fresh tarragon, minced
Kosher salt and freshly ground black or white pepper
Grated Parmigiano-Reggiano (for topping)
Lemon wedges, for serving
Directions
1. Prepare the Lobsters
On a work surface, dispatch each lobster by driving a chef’s knife into the crack behind the eyes and splitting the head.
Set up an ice bath. In a large stockpot with a steamer insert, bring 1 inch of water to a boil. Steam lobsters, covered, until just cooked, about 9 minutes. Transfer to ice bath to cool, 4 minutes.
Split lobsters lengthwise. Remove tomalley and roe (save or discard). Remove and discard the stomach sac.
Carefully extract tail, claw, and knuckle meat, keeping body shells intact. Cut meat into large chunks; refrigerate.
Reserve 4 halved shells from the large lobsters for serving. Place remaining shells, including the smaller lobster, aside for stock.
2. Make the Lobster Stock
In a large saucepan or Dutch oven, heat oil over medium-high. Add shallots, garlic, and celery; cook until softened, about 3 minutes.
Add lobster shells and cook until lightly browned, about 4 minutes. Stir in tomato paste; cook 1 minute.
Deglaze with brandy, scraping up browned bits; cook 2 minutes. Add water and tarragon. Simmer until reduced by half and flavorful, about 20 minutes, stirring occasionally.
Strain and discard solids. Reserve stock.
3. Prepare the Thermidor Sauce
In a sauté pan or saucier, melt butter over medium heat. Add shallot; cook until softened, 3 minutes.
Stir in flour and cayenne; cook 1 minute.
Gradually whisk in lobster stock, ensuring a smooth sauce. Stir in cream, mustard, and Gruyère; cook until cheese is melted.
Remove from heat. Stir in tarragon, season with salt and pepper. Transfer to container, press plastic wrap directly on surface, and chill.
4. Assemble and Cook
Preheat broiler, positioning rack 6 inches from heat source.
Drain lobster meat of any liquid. Combine with cooled Thermidor sauce.
Spoon mixture into reserved lobster shells. Top with Gruyère and Parmigiano-Reggiano.
Broil until browned and bubbling. If topping browns before meat is heated through, finish in a 350°F (175°C) oven until warmed.
5. Serve
Transfer lobsters to plates. Serve with lemon wedges.
Notes
The smaller lobster provides extra meat and additional shells for stock. If available, ask for a “cull” (a lobster missing a claw); it’s cheaper and works well here.
Equipment
Large stockpot with steamer insert
Dutch oven or soup pot
Sauté pan or saucier
Make-Ahead
Lobster meat, stock, and sauce can be prepared up to 1 day ahead and stored separately in airtight containers.
The dish can also be assembled (stuffed shells) ahead of time, refrigerated, and topped with cheese just before broiling.