Place ribs on a baking sheet and mix together ingredients for the rub, reserving two tablespoons for the BBQ sauce. Cover ribs with the rub and wrap ribs tightly in tinfoil. Bake ribs for two hours.
While ribs are in the oven make the BBQ sauce. Heat oil in a medium sized pot and cook onions until translucent. Add remaining ingredients and cook on medium-low for 30 mins. Using an immersion blender blitz the BBQ sauce until smooth.
Once ribs have baked for two hours, remove them from the oven, unwrap them and slather with BBQ sauce. Heat the BBQ to hight heat and grill, turning every few minutes until the ribs have developed a nice char.