Remove the medallions from the refrigerator in advance (half an hour in advance) so that they come to room temperature. Then spread with salt and pepper.
How to Cook Beef Tenderloin Medallions in Pan - Melt the butter and fry the garlic for 2 minutes on low heat. Then place the medallions in the pan and fry for 3 minutes. Turn the medallions over to the other side and add a little more butter to the pan. Fry the for another 2 minutes or until middle reaches 130-135 degrees F.
How to Cook Beef Tenderloin Medallions in Oven - Melt the butter and fry the garlic for 2 minutes on low heat. Then place the medallions in the pan and fry for 1 minute on each side to get a deep browning.
Preheat your oven to 400°F or 200°C. Transfer the skillet to the preheated oven until it reaches the optimal temp. of 130 degrees F.
Resting - Place the meat in foil and wrap tightly, leaving for 10 minutes.
How to Make Gravy - Place the chopped onion in a frying pan and fry for 5 minutes over medium heat, stirring occasionally. Add all-purpose flour, stir and cook for 2 minutes, stirring. Pour in the broth and stir the gravy, breaking up any lumps of flour.
After 3 minutes, when the gravy becomes thick, remove it from the heat. If the gravy is very thick, add a little more water or broth. Serve with gravy.