Heat olive oil in a large nonstick sauté pan over medium heat. Add the onion and garlic and sauté until tender (5-7 minutes).
Meanwhile, drain and rinse the jackfruit in a strainer. Cut away the core of the jackfruit (the tough triangular tip) and discard, reserving the soft, stringy flesh (see here for a photo). If desired, remove the jackfruit seeds/bulbs (you can eat these, but some people don't like the texture).
Mix together the brown sugar, chili powder, cumin, garlic powder, smoke salt, and cayenne pepper in a medium bowl. Add in the jackfruit flesh and toss to coat.
Add the seasoned jackfruit to the pan. Sauté for 5 minutes.
In a small bowl, whisk together the barbecue sauce and water. Pour over the jackfruit. Reduce the heat to low, cover, and simmer for 20-25 minutes, or until tender.
While the jackfruit simmers, toast the buns.
Remove the lid from the skillet and shred the jackfruit with a fork. Continue to simmer with the lid off for 5 minutes, or until the barbecue sauce is mostly absorbed.
NOTE: You can either enjoy the "pulled pork" as is OR spread it on a baking pan and bake at 350F degrees for 20 minutes. Readers have reported this extra step makes the texture even more "pork" like.
Fill each bun with a mound of BBQ jackfruit and top with garnishes of choice (ideas: pickled red onions, cilantro, mini cucumbers, etc).