Preheat oven to 400 °F (205 °C). Place tenderloin in a greased roasting pan. In a small bowl, combine 1 Tbsp (15 mL) of the maple syrup, mustard, garlic, rosemary and pepper. Brush over pork. Roast in preheated oven for about 25 minutes, or until a meat thermometer inserted in the thickest part of the tenderloin measures 155 °F (68 °C). Transfer tenderloin to a cutting board, tent with foil and let rest for 5-10 minutes to allow juices to redistribute and pork to reach an internal temperature of 160 °F (71 °C).
While pork is roasting, heat oil in a large skillet over medium heat. Add apples and sauté for 10 minutes, or until lightly browned. Reduce heat to low and add remaining 2 Tbsp (30 mL) of maple syrup and dried cranberries. Simmer, stirring occasionally, for 5 minutes, or until apples are tender and cranberries are plump.
Add water to the roasting pan and deglaze, scraping up any brown bits. Strain liquid into the apple mixture and stir to combine.
To serve, cut pork crosswise into thin slices. Top each serving with apple and cranberry sauce and garnish with a sprig of rosemary.