1. Heat the oil into a saucepan and sauté the shallots; add the vermouth and cook until the liquid has almost completely evaporated;
2. meanwhile, purée the tomatoes in a blender and put through a fine sieve;
3. add the tomatoes to the reduction; bring to a boil; reduce by one-third;
4. thicken lightly with the roux;
5. gradually whisk in the pieces of butter;
6. correct the seasoning; add salt and pepper to taste;
7. cook the linguine "al dente".

Presentation

1. Place the linguine in the centres of six pasta bowls;
2. pour the sauce all around;
3. place the snails on top; add the finely-chopped basil;
4. garnish each plate with a sprig of basil.