Lobster Thermidor
Lobster Thermidor

Lobster Thermidor

Preparation 20 to 25 minutes
Cooking time 12 minutes
Servings 4


  • 4 live lobsters, about 625 g (1 1/4 lb) each (1 lobster per person), or 2 large lobsters, 1 kg (2 lb) each (for 4 servings as an appetizer)
  • 25 ml (5 tsp) butter
  • 25 ml (5 tsp) flour
  • 410 ml (1 2/3 cup) boiling fish stock
  • 30 ml (2 tbsp) Dijon mustard
  • 15 ml (1 tbsp) cognac or brandy
  • 2.5 ml (1/2 tsp) paprika
  • Salt and ground black pepper
  • 180 ml (3/4 cup) Gruyère cheese, shredded


  1. Boil the 625 g lobsters in salted water for 10 to 12 minutes, or for 22 to 26 minutes for the 1 kg lobsters.
  2. Remove from water and leave aside to cool.  
  3. Meanwhile, melt the butter over low heat in a saucepan.
  4. Add the flour and gently stir for about 5 minutes to make a roux.  
  5. Pour the fish stock over the roux.
  6. Stir with a whisk to avoid making any lumps.
  7. Simmer over low heat for 10 minutes.
  8. Add half the Dijon mustard, the cognac and paprika and stir. Adjust the seasoning.
  9. Cut the lobsters in half lengthwise, remove the meat from the tail and claws (be careful not to damage the shells too much).
  10. Remove and discard the intestines and stomach.
  11. Brush the inside of the lobster shells with the rest of the Dijon mustard.  
  12. Cut the lobster meat into big pieces. 
  13. Add to the sauce. Gently stir.  
  14. Stuff the shells generously with this preparation. 
  15. Top with cheese.
  16. Place under the oven grill for a few minutes until the top of the lobsters is nicely browned.
  17. Serve with rice and a vegetable of your choice.


To avoid damaging the shell too much, use kitchen shears or even a steak knife. It will allow cutting the hard lobster shell in a cleaner way than with clippers or a smooth-edged knife.

Note: If the lobsters are of a different weight than suggested, cook 2 to 3 min./100 g (10 to 12 min./lb).

Availability in stores