For the ham rolls with horseradish vinaigrette in a jar, mix well the gervais or cream cheese with the horseradish finely chopped beforehand and salt and spread on the raw ham with the help of a pastry bag, then roll it up lengthwise.
Place the rolls in a shallow jar with a wide opening (e.g. a preserving jar) and cover with sunflower oil, adding fresh thyme or rosemary if necessary.
In this way, the rolls will keep in the refrigerator for at least 2-3 weeks.