Finely chop the onion and garlic. Heat a spoonful of oil in a large pan and gently sauté them until soft.
Meanwhile, cut the carrots and red/yellow pepper into chunks.
When the onion has softened, add the chopped veggies to the pan, together with the spices. Stir for about half a minute, then add the pastes. Stir again for a few seconds, then add enough water to cover the veggies, together with the stock cube.
Gently simmer for about ten minutes, or until the carrots are tender and the sauce has thickened a bit.
Meanwhile, shred the lamb into bite-sized pieces.Add these to the tomato sauce, when the carrots are tender.
Cook for about 5 minutes to warm the meat through, then stir in the chopped pistachio, mint and lemon zest.
Serve immediately.