Slice pork tenderloin crosswise into 16 slices. Place each pork slice between 2 sheets of plastic wrap; pound to 1/4-inch thickness using a meat mallet. Combine 1/4 cup coconut milk and 1 tablespoon red curry paste in a medium bowl. Add pork to bowl; toss. Cover and marinate in refrigerator 1 hour. Combine peanuts, 1/4 cup coconut milk, brown sugar, soy sauce, lime juice, and 1 tablespoon red curry paste. Preheat grill to medium-high. Remove pork from bag; discard marinade. Thread pork evenly onto 8 skewers; sprinkle evenly with kosher salt. Place skewers on a grill rack coated with cooking spray. Grill 3 minutes on each side. Serve with peanut sauce.