Preheat the oven to 160–170°C.
Heat your barbecue or pan (if the latter, add a little oil). Add the ribs and let them caramelize, then place in a roasting tray.
Add the onions to the barbecue or pan and char on both sides, then do the same with the whole leeks, celery, carrots and tomatoes.
Cut all the charred vegetables into quite thick chunks (around 2cm), on an angle. Add to the roasting tray with the chicken stock, honey, vinegar, bay leaves and chillies, then braise for 2½–3 hours.
When the meat is very tender, you want to make the cooking liquid and juices sticky. This may have happened already in the oven but, if it hasn’t, pour the liquid off into a saucepan and cook until reduced.
Pour the sauce over the ribs and sprinkle over the fennel fronds.