Gather the ingredients.

Whisk soy, Dijon, and rosemary together in a bowl. Place tenderloins into a resealable plastic bag.

Pour marinade into the resealable plastic bag with tenderloins. Coat tenderloins with marinade, squeeze out excess air, and seal the bag. Marinate in the refrigerator for 1 to 4 hours, shaking once or twice.

When ready to cook, set an oven rack about 4 inches from the heat source and preheat the oven's broiler.

Remove tenderloins from marinade and shake off excess; place onto a rack in a broiler pan. Discard remaining marinade.

Broil tenderloins in the preheated oven for 10 minutes.

Flip tenderloins and continue to broil until no longer pink in the center and the juices run clear, 10 to 12 more minutes. An instant-read thermometer inserted into the center should read at least 165 degrees F (74 degrees C).

Slice tenderloins and enjoy!