Photograph: Brett Stevens
Slice the celery and carrots into 2cm pieces. Halve the leeks lengthways, then wash, trim and slice into slightly longer pieces.
Place all the ingredients, apart from the flour, pancetta and oil, in a large bowl, making sure the wine covers the meat. Cover; leave in a cool place for 2 hours (or overnight in the fridge).
Preheat the oven to 140°C, fan 120°C, gas 1. Remove the meat and pat dry with kitchen paper. In a bowl, season the flour and toss the beef in it.
Fry the pancetta in a dry frying pan until golden. Remove the pancetta using a slotted spoon, leaving the fat. Brown the beef in the same pan in batches – use the fat remaining in the pan for the first batch and a little oil for the following batches. Transfer to an 8-litre ovenproof casserole (or 2 smaller ones).
Add the marinade and pancetta, and stir together. Bring to a simmer on the hob and boil for 2 minutes, then cover with a tight-fitting lid and transfer to the oven for 3 hours. Scatter with parsley. Serve with green vegetables and buttered new potatoes or noodles.
Get ahead: make up to 2 days ahead. It freezes well, too.