Take the leaves off the rosemary and on a large cutting board sprinkle the rosemary with the salt and with a large knife chop until the salt and rosemary are well combined and the rosemary is chopped very small. Take the pork tenderloin and roll in in the salt/rosemary mixture until completely covered.
Place on a plate and set in the fridge for at least 30 mins and up to 4 hours. This will dry marinade the pork. When you are ready to cook it, take it out of the fridge and slice into 3/4 inch medallions. Heat a cast iron or large pan of your choosing until hot and add a little olive oil to coat the bottom. Add the medallions to the pan making sure not to crowd them. (You may need a couple of rounds of this if you pan is small). Let the pork sear untouched for a couple of minutes and then flip them over and do the same on the other side. You should have nice color and the rosemary should smell amazing!!!
Once all of the pork is browned on both sides add it all back to the pan and take the red wine and pour it into the hot pan. Swish the pan and medallions around so they all get into the wine and let the pork cook in the wine for a few minutes. There will not be a lot of sauce as the pork will soak up the wine. Add more wine if needed so that the meat cooks in some liquid. It all depends on the size of the tenderloin.
Take out the medallions and serve with your favorite sides. This meal takes so little effort, has just 4 ingredients, and cooks in minutes! It is a keeper for sure!!