Heat oven to 150C/130C fan/gas 2.
Put the ribs in a roasting tin in a single
layer and just cover with water. Cover
with foil and cook for 1½ hrs. Drain well.
If you are not finishing these straight
away, cover and chill until ready to cook.
Meanwhile, fry the onion in the oil in
a pan until soft. Add the garlic, smoked
paprika and chilli powder and fry for 1 min.
Add the passata, purée, vinegar and
sugar and bring everything to a simmer.
Cook for 10 mins. If you are not using
this sauce straight away, cool and chill.
Heat oven to 220C/200C fan/gas 7.
Brush the ribs all over with the sauce and
lay on a baking sheet. Mix the potatoes
with the oil, rosemary and seasoning in a
large roasting tin. Roast for 40 mins on
a middle shelf, with the ribs on the shelf
above. Turn the ribs and potatoes
halfway, until both are nicely browned all
over. Tip the potatoes into a large bowl
sprinkle with the vinegar and serve hot,
warm or cold. Slice the ribs to serve and
put any extra sauce into bowls for dipping.