Preheat the oven to 400 degrees F.
Make the guacamole: In a medium bowl scoop the avocado flesh; mash with a fork or potato masher. Fold in the remaining ingredients. Add more salt, if desired. Refrigerate, covered until ready to serve.
Mix the shredded brisket with the barbecue sauce.
Brush olive oil to cover baking sheets. Lay 6 tortillas on the oiled sheet pans and top with equal amounts of brisket/barbecue sauce, cheese, jalapenos, to taste, and cilantro leaves. Top with the remaining tortillas. Brush the tops lightly with more olive oil.
Put the baking sheets in the oven and bake for about 5 to 8 minutes until the cheese melts and the tortillas are golden brown.
Serve sliced into wedges with the guacamole on the side.