Preheat oven to 350°.
Line a large baking sheet with aluminum foil, and arrange the onions down the center of the foil.
Combine the dry rib rub ingredients into a small bowl, and combine using a small whisk or a table fork.
Rinse and pat dry a slab of baby back ribs. Brush the ribs with 3-4-tbsp of balsamic glaze, rub half of the rib rub on the bottom of the baby back ribs. Lay the seasoned side of the baby back ribs onto the sliced onions, rub the remaining rib rub onto the top of the ribs.
Place the ribs into a 350° preheated oven onto the center rack, cook for 2 1/2-hours.
After 2 1/2-hours, brush the ribs with the strawberry simple syrup mixture and continue to cook the ribs for the remaining 30-minutes.
Remove the ribs from the oven and brush them using the strawberry barbecue sauce. and allow the ribs to rest for 15-minutes.
Serve with strawberry barbecue sauce.