Cook the chicken or use precooked rotisserie chicken. You can grill the chicken and dice or slow cook the chicken until fork tender (about 4 hours on medium-high heat). Once the chicken is cooked or rehydrated if you are using freeze dried chicken/pork, place the cooked meat into a bowl. Shred the chicken or break into bite sized pieces. Pour over the chicken the BBQ sauce, Sriracha, garlic powder, salt and Montreal Steak Seasoning. Stir until combined and set aside.
For the salsa, prepare the fresh pineapple and dice into small pieces and place in a bowl. If you don't have a lot of time you can use canned, drained pineapple tidbits instead. Dice the red bell pepper and red onion and place in the bowl. Tear the cilantro into pieces and add to the salsa. Juice the limes and salt the salsa. If you want to add an avocado to your tacos, peel that and slice into thin slices.
Heat a flat griddle to medium heat. Add several corn tortillas to the griddle. Put a small handful of cheese onto the taco. Add the cooked chicken and let the cheese melt and the chicken warm through. Serve the tacos with the fresh salsa and avocado and serve.