Step 1

Heat oil in a large saucepan over medium-high heat. Add mushrooms and three-quarters of the onions. Cook, stirring occasionally, for 4 to 5 minutes or until mushrooms are tender. Add curry paste and cook, stirring, for 1 minute or until aromatic.

Step 2

Add lamb. Stir until well coated in curry mixture. Cook, stirring occasionally, for 3 minutes or until lamb is browned. Add stock. Bring to a gentle boil. Reduce heat to medium. Simmer, uncovered, for 5 minutes. Stir in tomatoes.

Step 3

Combine cornflour and 1 tablespoon cold water. Stir into curry and bring to the boil. Reduce heat to medium-low. Cook for a further 2 to 3 minutes or until curry thickens.

Step 4

Spoon curry into a bowl. Top with sour cream and sprinkle with remaining onions. Serve with rice and warm naan bread.