Slice the pork shoulder into 1/2 inch slices and place in a bowl.
Add the achiote paste, chili powder, garlic powder, cumin, oregano, salt, pepper, vinegar, and pineapple juice. Mix well until free of lumps and to coat all the pork shoulder pieces.
Cover with plastic wrap and refrigerate for a minimum of 2 hours to marinate.
Preheat oven to 350 degrees F. Get your baking pan and line it with parchment paper.
Remove the marinated pork from the fridge and evenly arrange it in the baking sheet along with 2 slices of pineapples.
Bake for 1 1/2 hour or until the pork is slightly charred and the pineapples are roasted.
Assemble the tacos by putting pork pieces, pineapple, onions, cilantro, diced avocado, and salsa. Serve with lime wedges.