1. Split the lobsters in half starting from the head. Remove the gravel bag with a spoon. Chop the head into pieces.

2. In a pot, heat the olive oil. Season and add the pieces to color them over high heat, 5 minutes. Remove the tails.

3. Add the onion, carrot, and celery. Cook over low heat for 4 minutes.

4. Add the concentrated tomato paste, cognac, and reduce. Add the white wine and reduce by half. Pour in the fish stock and garlic. Cover and simmer for about 40 minutes.

5. Blend the bisque in a blender. Strain through a fine-mesh sieve, pressing to extract as much liquid as possible. Add the mussels and heat for 3 minutes.

6. Check the seasoning and serve.