For the sauce, finely dice the onion and fry in olive oil in a pan. Add the lobster paste, curry powder and tomato paste. Quarter the cocktail tomatoes, add them and fry them lightly. Dust with flour and brown lightly. Deglaze with cognac. Add the stock and cream and let the sauce reduce slightly. Stir in the Italian herbs and season with salt, pepper and sugar.
Wash the crayfish, drain them and add them to the sauce, heat but no longer boil. Serve with the pasta and Parmesan if you like.