Place the shallot, pepper, garlic, chilies, parsley, paprika, oregano, lemon zest and juice, vinegar and olive oil in a mini food processor and blitz until smooth. Set aside one third and mix the sugar into the remaining marinade.
Place the ribs in a baking sheet and cover with the marinade. Leave to marinade for at least 2 hours, or preferably overnight.
Preheat the oven to 160°C/fan 140°C/gas mark 3. Cover the ribs with tin foil and bake for 3½-4 hours, until completely soft when inserted with a knife. Turn the oven up to 200°C/fan 180°C/gas mark 6 and cook for a further 10-15 minutes, until sticky and deep golden all over. Leave to rest for 10 minutes before cutting into individual ribs and serving with the reserved sauce.