Step 1

Heat 1 tbsp oil in a large casserole over medium heat. Add lamb and cook, turning and allowing fat to render, until golden brown (12-15 minutes), then transfer to a plate. Strain fat through a fine sieve and reserve 30gm.

Step 2

Heat remaining oil in casserole over medium-high heat, add onion and carrot and cook, stirring occasionally, until golden brown (4-5 minutes). Deglaze pan with wine, scraping base of pan, then add tomato, thyme, rosemary, lamb and stock and cook until tender (2-2½ hours). Remove from heat and discard herbs. Remove the lamb (reserve liquid) and coarsely shred with two forks.

Step 3

Meanwhile, for duchess potato, place potato in a saucepan of cold salted water. Bring to the boil, then reduce heat to medium and simmer until very tender (5-7 minutes). Drain, then return to pan, mash until smooth and transfer to an electric mixer fitted with the paddle attachment. Beat in butter, yolks and cream until fluffy and season to taste.

Step 4

Preheat oven to 200°C. Melt reserved fat in a small saucepan over medium heat. Add flour and cook, stirring constantly, until sand-coloured (2-4 minutes). Ladle a little braising liquid into this roux and whisk until smooth (1 minute), then transfer roux to remaining braising liquid in casserole and stir to combine. Return lamb to casserole and stir to coat thoroughly.

Step 5

Transfer lamb mixture to a deep 26cm pie dish and cool briefly. Top lamb with an even layer of duchess potato and bake until potato is slightly puffed and golden (25-30 minutes). Serve hot.