The long braise the whole tradition is built on. Made properly it takes two days, and the second day is where it happens.
Into eight pieces — two drumsticks, two thighs, two wings, two breast portions. The backbone and ribcage go to the stock pot.
Everything for the marinade into a non-reactive bowl with the chicken, covered, in the fridge overnight.
Lift the pieces out and pat them dry with a cloth. Properly dry — wet chicken will not brown, and this chicken has spent twelve hours in liquid. Strain the marinade and keep the wine; discard the vegetables, they have given up everything they had.
Lardons into a heavy casserole over medium heat until the fat runs and they colour. Lift them out.
Chicken into the bacon fat in batches, skin down, until deep brown on both sides. This is the step that decides what colour the finished dish is. Lift out.
Small onions and mushrooms in the same fat until coloured. Lift them out too and set aside — they go back in at the very end, and if they cook for the full braise they disintegrate.
Butter into the casserole, then the flour, and cook it for two full minutes, stirring, until it smells like biscuits rather than raw flour. Tomato purée in for another minute.
The reserved wine, poured in slowly with the pan off the heat and whisked as it goes, then the stock. It will thicken as it comes back to a simmer.
Chicken and bacon back in, the liquid coming about three quarters of the way up the pieces. Lid on, into a 160 °C oven for an hour and a quarter.
Onions and mushrooms back in for the last fifteen minutes, uncovered. Taste for salt now, at the end, once the sauce has reduced — season it earlier and you will overshoot.
Cool it, refrigerate it overnight, reheat it gently the following day. The difference is not subtle. The sauce thickens as the gelatin from the bones sets and re-melts, and the meat, having sat in the sauce, tastes of it rather than sitting in it.
Use wine you would be willing to drink a glass of, but nothing expensive — the tannins and fruit that make a good bottle worth its price are largely destroyed by three hours of heat. A rough, dry, unoaked red is the right answer.
The overnight marinade can be skipped and the dish will still be good. Browning the garnish separately cannot be skipped, and neither can the two minutes of cooking the flour.