Preheat the oven to 200°C/Fan 180°C/Gas 6. In an ovenproof pan, fry the squash in the olive oil over a high heat until coloured. Season, then pop in the oven for 5–6 minutes. Remove from the oven and set aside.
Heat the grill to high. Place the lamb onto a baking tray, season, drizzle over a little olive oil and grill for 8 minutes, then rest.
Put a large pan of water on to boil and make the gnocchi. Mix together the potato, pumpkin, flour and egg yolks, then season. Roll into two 20cm-long sausage shapes, 2cm thick, using a little extra flour. Cut into 3cm pieces, plunge into boiling water for 1 minute, then drain.
Heat a large frying pan over a medium heat and, once hot, add the veal jus, sherry vinegar and lemon juice. Bring to the boil and add the butter. Stir through the gnocchi and season.
Heat the vegetable oil in a pan to 180°C and deep-fry the sage leaves for about 30 seconds until translucent.
To serve, place the sliced squash on a platter, top with the lamb steaks, gnocchi and sauce, then scatter over the crispy sage leaves.