Preheat the oven to 300°F. Arrange the chicken thighs in a square 8-inch baking dish. Make several shallow cuts into the chicken using a sharp knife.
In a mixing bowl, whisk together the tomato paste, balsamic vinegar, sea salt, black pepper, garlic powder, smoked paprika, and stevia glycerite to create the barbecue sauce.
Evenly coat the chicken with the prepared sauce, ensuring the mixture seeps into the slits. Use your hands for thorough application.
Seal the baking dish securely with a double layer of aluminum foil. Place in the oven and bake for 3 hours, until the chicken becomes extremely tender and aromatic.
Remove the dish from the oven and carefully lift the foil—be cautious of the hot steam. Let the chicken rest for 5 minutes to cool slightly.
Shred the chicken directly in the dish using two forks or a rubber spatula. Mix well so the meat is fully incorporated with the sauce.
Serve hot and enjoy immediately.