In a food processor, whirl garlic, 1/2 cup soy sauce, the oil, sugar, and five-spice powder until blended. Put pork tenderloin in a shallow dish or zip-lock plastic bag and slowly add soy mixture. Turn pork over to coat in marinade. Cover and refrigerate at least 1 hour and as long as overnight.
Preheat broiler to high. Transfer pork to a roasting pan lined with foil; discard marinade. Position roasting pan 6 to 8 inches below broiler and cook until meat begins to brown on top, about 10 minutes. Turn pork over, move roasting pan to center oven rack, and reduce heat to 350°. Roast meat until a thermometer inserted in center of thickest part reaches 150°, about 30 minutes (meat should be slightly pink; cut to check). Transfer to a cutting board, loosely cover with foil, and let rest 10 minutes.
Meanwhile, in a small bowl whisk together plum sauce, mustard, remaining 2 tablespoons soy sauce, and the Sriracha; transfer sauce to a serving dish.
To assemble wraps, slice tenderloin very thinly and arrange 1 slice on each radicchio leaf. Top with green onion and radish ribbons. Tuck up the bottom of each leaf and fold sides inward to eat. Drizzle with or dip into sauce.
Note: Nutritional analysis is per serving.