Maple and Garlic Marinated Pork Tenderloin

Whisk onion, maple syrup, Dijon mustard, garlic, horseradish, sesame oil, and black pepper together in a shallow bowl. Add pork to marinade and turn to coat. Cover bowl with plastic wrap and marinate pork, 8 hours to overnight.

Remove pork from marinade and pour marinade into a small saucepan. Cook marinade over medium-low heat until bubbling, about 5 minutes.

Heat olive oil in a skillet over medium-high heat. Cook pork in the hot oil, basting with marinade, until browned, 2 to 3 minutes per side. Reduce heat to low and cook pork, basting occasionally with marinade, until no longer pink in the center, 15 to 25 minutes. An instant-read thermometer inserted into the center should read at least 145 degrees F (63 degrees C).