Heat 2 tsp olive oil in a skillet. Add shallots and apples and sauté until apples are tender, approximately 5 minutes. Add garlic and sauté for 1 minute. Add salt and pepper. Combine with currants and pecans and put stuffing aside.
In a separate bowl, combine balsamic vinegar, Dijon mustard and mix well, add in remaining 2 tbsp olive oil and mix until well combined.
Cut a slit down the length of each tenderloin. Be careful not to slice all the way through. Cover with plastic wrap and using a meat mallet flatten to approximately 1/2 inch thickness.
Drizzle inside of the pork tenderloins with balsamic mixture. Layer one cup of arugula and half the stuffing on each tenderloin. Gently close tenderloins securing with either toothpicks or string.
Rub the remaining balsamic mixture all over tenderloins. Place on a foil covered baking sheet coated with cooking spray. Season with salt and pepper. Bake at 425 degrees for 20-25 minutes or until a meat thermometer measures 150-160 degrees. Be careful not to overcook the pork.
Once cooked, remove from oven and let rest for approximately 5 minutes. Slice each tenderloin and arrange on a serving dish over a bed of baby arugula (optional).