160ºC, fan 140ºC, gas 3. Heat the oil in a large flameproof casserole with a lid.
2. Add the onion and celery to the casserole and fry for a few minutes, then add the garlic, carrots and squash and fry for a further 2-3 minutes.
3. Add the tomatoes, stock and sugar. Give it all a good stir then cover and place in the oven for 20 minutes.
4. Remove from the oven and stir in the green beans. Return to the oven, uncovered, and cook for a further 20 minutes until the sauce has thickened; add the lamb for the final 10 minutes to warm through. Serve with the mashed potato.
Flavour leftover lamb with teriyaki and ginger in this Speedy lamb stir-fry.