Marmite carbonnade

Ingredients

• 85 g butter unsalted for spreading
• 4  onion halved sliced
• 3  garlic clove peeled smashed
• 1.5 kg fat-trimmed beef flank steak cut into large cubes
• 850 ml beef stock 
• 1.5 tbsp flour plain
• 400 ml porter canned
• 10  thyme sprigs 
• 2  bay leaves 
• 1 tbsp g muscovado sugar light
• 2 tsp red wine vinegar 
• 2 tbsp catsup (optional, see Know-how, below)
• 1  celery trimmed sliced
• 2 tsp yeast extract spread 
• 25 slices bread french fine thin ()

Equipment

• bowl
• frying pan
• oven

Directions

1. Heat oven to 180C/fan 160C/gas
2. Melt half the butter in a large cast-iron casserole over a medium heat, add the onions, then fry for 8-12 mins until golden, stirring occasionally.
3. Add the garlic just before the end, then transfer everything to a bowl. Turn the heat up a little, season the beef with salt and pepper and seal it in batches so as not to overcrowd the pan, adding a knob of the remaining butter with each one. Deglaze the pan with a little stock as you go along.
4. Return the onions and beef to the pan, sprinkle over the flour, stir, then pour over the Guinness and stock.
5. Add the herbs, sugar, vinegar, mushroom ketchup (if using) and some seasoning. Bring the liquid to the boil, cover, then cook in the oven for 1 hrs. If serving on the day, skim the fat off at this stage.
6. Remove the casserole and turn the oven up to 200C/fan 180C/gas
7. Discard the herbs, check for seasoning, then add the celery.
8. Mix the remaining butter with about 2 tsp Marmite, then spread it over the slices of French bread on one side. Arrange the slices, Marmite-side up, overlapping on top of the casserole, then return to the oven for another 30-40 mins until the toasts are golden and crisp.
9. Serve straight away.