Preheat oven to 375F and line a rectangle loaf pan with a sheet of parchment paper to cover the base and the two longer sides of the pan (makes pulling the loaf out of the pan easier).
In a small bowl, add and mix all the BBQ sauce ingredients together with a spoon until smooth and well combined.
In a large bowl, roughly mash the cooked lentils, just to break them up, with a fork or potato masher. Add the oats, chopped onion, garlic powder, liquid aminos or soy sauce and all the bbq sauce EXCEPT 2 tbsp (to save for the glaze topping) and mix everything together until well combined.
Transfer the lentil meatloaf mixture to the baking pan and push down to evenly spread it out in the pan. Cover the top of the loaf with the 2 tbsp of the BBQ sauce. Place the loaf into the oven center rack to bake for 25 minutes.
Allow to cool down for 5 to 10 minutes before slicing and eating and store leftovers in fridge for up to 2 weeks.