Place the sliced onions and diced pineapple into the bottom of the slow cooker. 

In a small bowl, combine the chili powder, onion powder, garlic powder, salt, oregano and cinnamon. 

Rub all sides of the pork ribs with the spice mixture. 

Place the spice-coated ribs on top of onions and pineapple in the slow cooker. 

Cover and cook on high for 4 hours or low for 7 hours. 

Once the pork is cooked, turn off your slow cooker and remove any bones from the meat. You can also remove any large pieces of fat from the meat, if you’d like. 

Place the meat on a cutting board and chop it into bite sized pieces using a sharp knife or use 2 forks to pull the meat apart. 

Place meat in a large bowl. 

Using a slotted spoon or a kitchen spider, remove as much of the onion and pineapple as you can from the liquid in the slow cooker and add it to the pulled pork. 

Mix everything up. 

Serve on warm, flour tortillas with your favorite taco fixings.