Preheat the oven to 300 degrees F, with a rack placed in the center of the oven. Line a large rimmed baking sheet with aluminum foil and set aside.
Flip one rack of baby back ribs over and insert the tip of a butter knife under the membrane that covers the back of the rack. Wiggle the knife to loosen the membrane. Use a paper towel to hold one the and pull it off. Repeat with remaining rack.
Combine the seasonings in a small bowl and mix well with a spoon or small whisk. Sprinkle the rub generously on both sides of the baby back ribs. Place the ribs bone side down on the baking sheet and bake for about 2 hours, or until the ribs are slack when you lift them and the meat is almost ready to fall off the bone.
While the ribs are in the oven, make the barbecue sauce. In a medium saucepan over medium heat, stir together the blueberries, honey and balsamic vinegar. Bring to a boil, then lower heat to a simmer, and cook until the blueberries have burst and released their juices, about 5 minutes. Add the red pepper flakes, cayenne pepper (add in increments if you are sensitive to spice), shallots and garlic and let it cook for about 5-7 minutes more. If you have an immersion blender, blend the sauce together to puree the sauce into a smoother consistency. You may also use a blender or a masher.
Stir in the molasses, salt and pepper, and continue simmering the sauce until it has thickened, about 15-20 minutes. Adjust seasoning if necessary. Remove from heat and let it cool; it will thicken as it sits. The sauce may be used right away or stored in an airtight container in the refrigerator after cooling completely.
Preheat the grill to medium-high heat.
When the ribs are tender, remove from the oven. Brush the ribs with barbecue sauce on both sides. Reserve the remaining sauce for serving. Place the ribs on the grill, and cook for about 5 minutes, or until the ribs are caramelized, turning periodcally. Transfer the ribs onto a cutting board and brush with more sauce. Let it sit for about 5-10 minutes, then cut the ribs. Serve immediately along with the reserved sauce.