Heat a small frying pan over medium heat with no oil. Add the coriander seeds, cumin seeds, peppercorns, fenugreek seeds, and cardamom pods (both types), cinnamon stick, and cloves.

Toast for 1½ to 2 minutes, stirring frequently, until fragrant and the seeds begin to colour — do not let them burn.

Tip into a spice grinder or mortar and pestle and grind until you have a coarse powder. You should have about 2 tablespoons of ground spice.

Transfer to a small bowl and stir through the ground ginger and turmeric. Set aside.

Heat the oil in a large heavy-based pot or Dutch oven over medium-high heat. Working in batches so you don't overcrowd the pan, brown the lamb cubes on all sides — about 3 minutes per batch. Transfer to a plate.

Reduce heat to medium. Add the diced onion to the same pot and cook for 4 to 5 minutes, stirring occasionally, until softened and lightly golden.

Add the minced garlic and cook for 1 minute until fragrant.

Stir in the tomato paste and cook for 1 minute, coating the onion well.

Add the ground spice blend and stir constantly for 1 minute to bloom the spices.

Return the lamb and any resting juices to the pot. Pour in the chopped tomatoes and stock. Add the bay leaves.

Bring to a simmer, then reduce heat to low. Cover partially and simmer gently for 1 hour, stirring occasionally, until the lamb is very tender and the sauce has reduced slightly.

Stir the yoghurt into the curry in a thin stream, stirring constantly to prevent curdling. The sauce should thicken slightly and take on a richer, creamier character.

Taste and adjust seasoning with salt. Stir in the sugar and lemon juice.

Simmer uncovered for a further 5 minutes until the sauce reaches your desired consistency — it should coat the back of a spoon.

Discard the bay leaves. Scatter fresh coriander leaves over the top and serve with basmati rice or warm naan.