Step 1

For pastry, process flour and lard in a food processor until mixture just comes together. With the motor running, add yolks and 60-80ml iced water and process until lumps start to form. Turn out dough onto a bench and knead with the heel of your hand until it just comes together. Wrap and refrigerate to rest and chill (1 hour).

Step 2

Preheat oven to 150°C. Heat 2 tbsp oil in a casserole or deep cast-iron frying pan over medium-high heat. Dust lamb with flour, shaking off excess, add to pan, in batches, and cook, turning occasionally, until golden brown (2-3 minutes each side; if lamb starts to burn, reduce heat and add extra oil if needed). Remove lamb and set aside. Add rosemary to pan and stir until fragrant (2-5 seconds), then add mustard and stir to combine. Deglaze pan with wine and vermouth, scraping base, then reduce by half (3-4 minutes). Add stock and bring to a simmer, then return lamb to pan, cover tightly with foil or a lid and braise in oven until lamb is tender and falling off the bone (1¾-2 hours). Remove lamb (reserve liquid in pan), cool slightly, then coarsely shred (discard bones). Cool.

Step 3

Meanwhile, heat remaining oil in a casserole over medium-high heat and cook shallots, stirring occasionally, until golden and caramelised (8-12 minutes). Remove shallots and set aside. Add fennel to pan and cook, stirring occasionally, until tender (5 minutes). Set aside.

Step 4

Add shallots to reserved braising liquid and cook over medium heat until tender and liquid has reduced to a thick sauce (14-18 minutes). Return lamb to pan and season to taste (not too much, as Manchego is quite salty). Cool, then refrigerate until chilled (1 hour).

Step 5

Preheat oven to 200°C. Roll out dough between 2 sheets of baking paper to fit a 27cm-diameter cast-iron frying pan or pie dish. (Reserve trimmings to decorate if desired.) Spoon lamb mixture into pan, top with fennel, then Manchego, then pastry. Trim pastry with a sharp knife or pinch to create an edge. (Pie can be made ahead to this stage, covered and refrigerated for up to 1 day.) Cut a hole in the centre (an apple corer works well). Brush with eggwash, scatter with fennel seeds and salt flakes, then bake until golden and bubbling (35-40 minutes). Rest for 5-10 minutes, then serve.