Dry rub: add the garlic powder, onion powder, mustard powder, paprika, salt and pepper to a small glass and use a mini wish to stir and combine.
Ribs: use kitchen tongs to lay the ribs out flat in one layer on a chopping board.
Rub onto ribs: coat the ribs all over with the dry rub, rubbing it into the meat as you go. Use tongs to flip the rubs and repeat for the other side, top and bottom.
Olive oil: lightly spray the base and sides of the slow cooker with olive oil.
Worcestershire sauce: pour the sauce into the base of the slow cooker.
Ribs into slow cooker: use kitchen tongs to place ribs into slow cooker side by side. They can overlap if there is not enough room.
Cook: place the lid on the slow cooker and set the temperature to high for 3-4 hours (or low for 6-8 hours).
Remove: once cooked, remove the lid and use a slotted silicon turner slid under the ribs to transfer them to a baking rack.
Grill: place the ribs onto the top shelf of the oven and grill for 12 mins at 200°C 392° F6 till lightly browned around the edges.
Serve and enjoy: use oven mits to remove the baking tray from the oven and rest on a heat proof surface. Rest for 1 to 2 mins before plating and serving.