Brush the honey Dijon mustard onto the pork tenderloin.
Cut slices across the tenderloin, about 3/4 –inch apart, going as deep as possible without cutting all the way through.
Stuff each cut with a half-moon slice of apple.
Sprinkle the chopped walnuts and sage over the tenderloin. Drizzle over the maple syrup and bake for 25-30 minutes, until the internal temperature reads 145 degrees.
Meanwhile, cook the applesauce and apple cider in a small pan over medium heat. Reduce the mixture by half and pour over the tenderloin to serve.
