Pre-heat oven to 450°F.
Place pork loin on a cutting board and make a series of small, parallel incisions along the length of meat.
Transfer to a large baking dish or baking sheet
Fill each incision with ½ pineapple ring.
In a medium bowl, pour barbecue sauce and ½ reserved pineapple juice, more of less as desired.
Stir in red bell pepper, jalapeno, garlic and red onion; mx thoroughly.
Pour sauce over pork loin.
Place in oven and bake for 10 – 12 minutes.
Lower heat to 350°F and cook for another 35 minutes or until pork is cooked through.
Internal temperature should be between 150°F – 160°F.
Remove from oven and top with green onions, if using.
