Heat oil in a large, heavy-based saucepan on high heat.

Cook lamb in batches for 2-3 minutes each, until browned, and set aside.

Add onions to the saucepan and saute for 4-5 minutes, until tender and lightly golden.

Stir in cooking sauce and chicken stock.

Bring the mixture to a boil, then reduce heat to low.

Add the browned lamb back to the saucepan and simmer, covered, for 30 minutes, until the meat is tender.

Add the potatoes and cook, covered, for 25 minutes, until tender.

Stir in the spinach leaves and cook for 3 minutes, until wilted.

Serve the curry with poppadums.