Place the coriander seeds, ½ teaspoon mustard seeds, cumin seeds, black peppercorns, fennel seeds, cloves and salt in a pestle and mortar or spice blender and grind to a powder.
Stir in the turmeric and chilli powder.
In a large mixing bowl, combine the madras powder with the cubed steak and leave to one side whilst you prepare the sauce.
Heat the oil in a non stick frying pan and add 1 teaspoon mustard seeds.
Once the mustard seeds start to pop, add the chopped onion and curry leaves and cook over a medium heat for 7-10 minutes until the onions are soft.
Add the grated ginger, crushed garlic, ground cinnamon and hot chilli powder and whole chilli and cook for a minute.
Pour into the slow cooker.
Wipe the pan with a paper towel, add the other tablespoon of oil and sear the spiced beef over a medium to high heat, until all sides of the cubes of beef are golden. This takes approx 3-5 minutes.
Tip the beef into the slow cooker, pour the water in the pan and then add to the slow cooker to get all the beef flavour from the frying pan.
Add the tomatoes and tamarind pulp to the slow cooker. Stir then place the lid on and cook on a low heat for 8 hours.
Check the beef is tender, and serve with rice and naan bread.
Store any leftovers in the fridge for up to 3 days or freeze for up to 3 months.