Preheat the oven to 250–275°C (which is very hot, this takes some time).
Mix the garlic, thyme, pepper, salt and olive oil. Massage this mixture all over the meat.
Put the pork tenderloins in a roasting pan, just big enough so they almost touch each other. Place the pan near the bottom of your oven. After 10 minutes turn them. After 8 minutes — or when the internal temperature is at 68°C — take them out of the oven and let them rest for 10 minutes — the temperature should be 71°C now.
Slice them up, and serve with mashed potatoes. If you add some water to the tray and scrape the bottom, you have a simple, yet tasty sauce.