First, prepare the marinade for the pork loin. In a bowl mix the olive oil, mustard, finely chopped garlic, chopped rosemary and ground thyme. Mix all the ingredients well, so the flavors will uniform. Place the pork loin in a container and spread the marinade uniformly over the entire surface. Cover and leave to marinate in the refrigerator for at least 2 hours or, preferably, during the night.