Step 1

Put cardamom, peppercorns, cumin, coriander, mustard seeds and chilli flakes in a dry frying pan over medium heat. Cook, stirring for 3 minutes. Remove from heat.

Step 2

Spoon spices and turmeric into a spice grinder (or mortar and pestle) and grind to a powder.

Step 3

Heat a non-stick frying pan over medium heat.

Step 4

Add oil and saute the onion until it softens, and add garlic and ginger.

Step 5

Cook, stirring for 2 minutes.

Step 6

Add sweet potato and toss in spice mixture.

Step 7

Add coconut milk and stock and bring to the boil. Reduce heat and simmer, partially covered, for 12 to 15 minutes or until sweet potato is tender.

Step 8

Just before serving, add spinach and cashews and toss for 1 minute.

Step 9

Serve with hot cooked basmati rice.