Preheat oven to 325 degrees Fahrenheit.

Heat olive oil in a large frying pan over medium heat. Place flanken pieces in the frying pan and sprinkle with kosher salt and pepper. Brown the flanken for five minutes per side, then transfer to a 9- x 13-inch (20- x 30-centimeter) baking pan.

Combine all smoky barbecue sauce ingredients in a medium-sized bowl. Pour over the browned flanken.

Cover the pan tightly with aluminum foil and bake for two and a half to three hours, until tender and soft.

While the meat is still hot, shred it with two forks. (At this point you can refrigerate the meat until ready to serve.)

Fill each taco shell with shredded smoky flanken. Place three filled tacos on each plate. Garnish as desired.