Heat up the oil in a large saucepan over medium-high heat.
Add the diced onion and pepper to the pan and saute for 3 to 4 minutes.
Add the garlic powder and saute for another 1 to 2 minutes.
Add the ground beef to the pan and fry until it is browned.
Add the canned tomatoes, tomato puree, hot chile powder, brown sugar, barbecue sauce, Worcestershire sauce, and salt and pepper, to taste, to the pan.
Mix everything well and then turn the heat down to medium-low. Let the mixture gently simmer for 30 minutes. Add a splash of water if the mixture begins to stick to the pan.
Take the sloppy Joe mixture off the heat.
Assemble the tacos by adding the sour cream, sloppy Joe mixture, grated cheese, diced tomato, avocado, and fresh cilantro to the tortillas.