On a 24-hour-or-so flight to the Adelaide Food Festival the other month, my travelling partner Matthew Fort was reminiscing about his late mother Jean Fort's passion for cooking and some of the dishes she used to cook. Anyway, this recipe sounded eminently borrowable and by pure coincidence Matthew and I had lunch arranged just after we took the pictures for this article, so he was able to give it his thumbs up. It makes an admirable light supper dish – Matthew wolfed it down, and declared it a dish true to the spirit of the original, if slightly fancier.
4 medium to large baking potatoes
4 lambs' kidneys, trimmed
2 shallots, peeled, halved and finely chopped
100g butter, or more if you wish
2tsp grain mustard
1tsp Dijon mustard
1tbsp dry sherry
100ml beef stock
Preheat the oven to 200C/gas mark 6. Bake the potatoes directly on the oven rack for about an hour or until soft. Leave until cool enough to handle, then cut about a third off the top and carefully scoop out the main part, leaving the skin intact.
Mash the potato with butter with a fork and season to taste. Return the skins and tops to the oven to crisp up for 10-15 minutes, then refill with the potato, place the tops back on and keep warm in a low oven.
Meanwhile, melt a knob of butter in a pan and gently cook the shallots for a minute, add the mustards, sherry and stock and simmer until it has reduced down to about 2-3 tablespoons – then stir in a couple of knobs of butter.
While you are making the sauce, heat some butter in a frying pan, season the kidneys and cook them for 3-4 minutes, turning them as they are cooking and keeping them nice and pink.
To serve, slice the kidneys 3 or 4 times vertically, remove the tops from the potato and push the kidney into the potato; spoon over a little sauce. Place the lids back on or serve them on the side.