Preheat oven to 400 degrees F. Tie pieces of tenderloin together, opposite ends touching, using kitchen twine. (Tying the tenderloins together will make it more uniform in size, cooking more evenly.) Combine spices and lemon zest, rub on tenderloin. In a 12” cast iron skillet, heat olive oil over medium high heat, until shimmering. Add pork tenderloin and sear on 4 sides. Add potatoes around the perimeter of the skillet. (Halve potatoes that are bigger than a ping pong ball). Toss around in oil to coat. Sprinkle potatoes only, with seasoned salt. Mix around until covered with oil and seasoning. Place entire skillet into a preheated 400 degree oven to cook until center of tenderloin reaches 145 degrees F. Remove from oven, place pork onto a serving platter. Remove potatoes and place onto serving platter as well. Place skillet on stovetop over medium heat. Add onion and garlic, cook until tender, 1 minute, stirring frequently. Add chicken stock, red wine vinegar and bring to a boil. Continue to boil until mixture has thickened slightly 3 minutes. Remove from heat, add butter, stir well. Remove kitchen twine, slice pork, serve with sauce and potatoes (and green veggie!).