Joint the rabbits (or ask the butcher to do it. If you bought your rabbits from the supermarket, they will probably be pre-jointed, but they’ll also be farmed – tender but not so tasty).
Cut the shoulders and legs off, and cut them in halves at the elbows and knees. Turn each rabbit so its backbone is on the board. Put a knife across the body, below the ribcage, and whack the back of the knife with a rolling pin. If you’ve done it hard enough, you will have cut the rabbit in two.
Do the same thing at the other end to chop the pelvis off. Throw away the rib cages and pelvises. You will be left with a rectangular bit of the rabbit’s back, about 10cm long. Chop that in half, across the spine, giving you 10 pieces from each rabbit.
In a large mixing bowl, combine the mustard powder and flour with a few pinches of sea salt and black pepper. Toss all the rabbit pieces in the seasoning mix until well coated.
Peel and halve the onions. Trim and chop the celery, then peel the carrots.
Melt the butter in a large, shallow sauté pan over a medium heat. Add the rabbit and brown evenly on all sides, adding butter as required.
Add the onions, celery, carrots and thyme, and cook gently until soft and fragrant.
Pour over the ale, topping up with enough water to cover. Simmer gently for about 45 minutes, or until the meat is tender, adding water if the liquid gets low.
Once cooked, simmer the liquid to thicken, and stir in the mustard before serving with crusty bread and a watercress salad.