Place first 15 ingredients in a blender or food processor, and process until smooth.
Slice pork lengthwise, cutting to, but not through, other side. Open halves, laying each side flat. Slice each half lengthwise, cutting to, but not through, other side; open flat. Combine pork and green onion mixture in a dish or large zip-top plastic bag. Cover or seal; marinate in refrigerator 3 to 24 hours. Remove pork from dish or bag; discard remaining marinade.
Place pork on grill rack coated with cooking spray; grill 8 minutes on each side or until meat thermometer registers 160° (slightly pink).
This fiery barbecue was invented by runaway slaves as a means of preserving meats without refrigeration. Here, we butterfly the pork tenderloin to increase the surface area for the Scotch bonnet pepper marinade to penetrate.