Serves 4-6:
Clean and trim the meat of excess fat.
Slice the meat across the grain, about 0.8 – 1 cm thick. Season with salt and pepper.
Heat a small amount of the fat in a frying pan. As soon as the fat heats up brown the beef slices on both sides. Don’t overcrowd the pan and fry the beef in batches, adding small amounts of the fat as you go.
In the meantime put the sliced onions in a casserole dish. Set over a medium heat adding a knob of butter (or lard or a tablespoon or so of olive oil). Once the fat has melted reduce the heat, season with some salt (that step will help the onions to release some moisture allowing to cook slowly without frying) and start stirring. Cook for about 20 minutes or until the the sliced onion turns soft and lightly golden in colour.
With a slotted or a large spoon transfer the onions into a bowl or a plate.
Add a little bit of the fat and as soon as it melts stir in the flour. Cook, stirring all the while, over a low heat until the roux begins to darken slightly.
Now start diluting the roux with the beer, pouring in a small amount of it first, once that has been full absorbed add a bit more of the beer, and once you obtain a creamy consistency of the roux pour in the rest of the beer. Season with some salt and pepper, bring to the boil and add the sugar and the vinegar. Now simmer on a low heat for about 15 minutes stirring often.
Preheat the oven to 170 C / Static.
Transfer the onions and the browned meat (along with its juices) into the casserole dish, pour in the the stock, add the herbs and the bay leaf. Give everything a good stir, cover with the lid and bake in the oven for 3 hours, checking on the meat every 30 minutes or so.
The meat by that time should be tender and the sauce turn deliciously dark golden in colour. Check the dish for seasoning, remove and discard the bouquet garni.
Serve your carbonnade with boiled baby potatoes (garnished with freshly chopped parsley or dill) and a crunchy green salad on the side.