Cooking a lean roast like pork tenderloin in a slow cooker is tricky because it can quickly turn overcooked and dry. We discovered that nestling two tenderloins side by side, alternating the narrow and thicker ends, helped to insulate the meat and prevented it from overcooking.
Once we had the method in hand, we developed the flavor, coating the pork with a teriyaki glaze made with equal parts sugar and soy sauce and seasoned with fresh ginger, garlic, and mirin.
To ensure a properly clingy glaze, we simply thickened the sauce with some cornstarch before applying it to the pork, and then we ran the tenderloins under the broiler before serving.
To prevent the pork from overcooking under the broiler, we removed it from the slow cooker just shy of 145 F. You will need an oval slow cooker for this recipe. Because they are cooked gently and not browned, the tenderloins will be rosy throughout. Check the tenderloins’ temperature after 1 hour of cooking and continue to monitor until they register 145 F.