Preheat oven to 350°F (190°C). Mix mustard and peanut butter in a small dish and set aside. Season pork tenderloin with salt and pepper. Heat canola oil in a large skillet on medium-high heat and sear pork on all sides until browned.
Spread peanut butter mixture evenly over pork and roll tenderloin in peanuts. Place on parchment-paper-lined baking sheet and roast for 15 to 20 min., until golden and temperature reaches 160°F (71°C)) on a meat thermometer.
Let pork rest 5 min., slice, garnish with green onions and serve.