In a small bowl, add brown sugar, paprika, chili powder, onion powder, salt, cumin and pepper. Stir until well combined. Pat brisket dry with a paper towel, then rub with olive oil until completely coated. Once coated, evenly rub spice mixture all over brisket. Let stand for one hour. In an Instant Pot, mix barbeque sauce with broth, then add brisket. Set Instant Pot to “Pressure Cook” setting and set timer for 1 hour and 15 minutes. When cooking cycle is complete, carefully release pressure. Transfer brisket to cutting board. Cover with foil and let sit for 10 minutes. Set Instant Pot to “Sauté” setting and cook for 8 to 10 minutes or until liquid is reduced and thickened. After 10 minutes has passed, using two forks, shred meat and return to Instant Pot. Set to “Keep Warm” setting until ready to serve. Assemble each tortilla with an even distribution of brisket, pickled onions, avocado and sour cream. Tip: For a casual feast, serve with Mexican street corn and a creamy coleslaw. To make pickled onions, combine one-half cup red wine vinegar, one-fourth cup water, one teaspoon salt in a saucepan; bring to a boil. Pour over sliced onions in small bowl; let stand for at least 30 minutes.