We put the snails in a bowl with water until their heads are out of the shell (we don’t use them if they don’t come out) and we wash them very well several times. We put the snails in boiling water together with plenty of salt. When the water begins to foam, change it with a clean one, pour the vinegar and leave it for another 10 minutes. Remove the snails from the heat and rinse them with cold water. Salt the snails and flour them well. In a frying pan, place the olive oil and when it is in the appropriate temperature put the snails with their openings facing the pan and fry them for 3-4 minutes. Add rosemary, salt, pepper, stir them and 2 minutes later add the wine. Let them come to the boil and they are ready to serve.