Sauté the onion in olive oil and add the sSaute the onion in olive oil and add the snails and potatoes in the pot. Cover with water and salt. Let them simmer. Just before the food is done, pour the trahanas into the pot. Continue boiling for a while and then serve.nails and potatoes in the pot. Cover with water and salt. Let them simmer. Just before the food is done, pour the trahanàs into the pot. Continue boiling for a while and then serve.