Prep the ribs by removing the membrane from the back and cutting in half.
Mix the dry rub ingredients together in a bowl and rub well all into the ribs. Cover each rib section in a foil parcel and cook for 2 1/2 hours at 140°C in a conventional oven.
For the BBQ sauce, toast the smoked paprika in a dry pan until fragrant, add the honey and sugar and cook to caramelise.
Add the vinegars and orange juice and cook for a further 3-4 minutes.
Add the ketchup and leave on a very low heat for around 15 minutes. Set to one side until required.
Cut the celeriac into thin strips and the radishes into thin rounds before mixing together with the mayo, mustard and parsley.
Once the ribs are cooked, remove them from their foil parcels and place on a cast iron tray. Brush liberally with BBQ sauce and cook in Roccbox for 4 minutes or so on each side, until nicely charred and caramelised.