For the Curry Paste:

1. Heat a medium sized frying pan over medium heat and dry roast the coriander seeds and cumin seeds until they start to smell fragrant.
2. Transfer the seeds into a pestle and mortar and grind into a fine powder. Pour the ground spice into a small bowl and set aside. Alternatively grind the seeds in an electric grinder.
3. Place the chilies in the pestle and mortar with the salt and grind for 1 -2 minutes. Then add the rest of the ingredients one at time, grinding between every addition.
4. You should have a fine paste. Add a splash of water if the mixture is too dry. Stir in the ground spices until well combined and set your curry paste aside for later.

For the Curry:

1. In a large pot over medium/low heat, combine the coconut cream with the curry paste and simmer for 5 minutes. Add the palm sugar, fish sauce and stock and bring to a boil. Stir in the tomatoes and onion, reducing the heat to a simmer until soft.
2. Add the prawns and potatoes and cook on a low simmer for 15 - 20 minutes or until the potatoes are soft and the prawns have turned pink.

For the Cucumber Relish:

1. In a small saucepan, simmer the vinegar, water, sugar, and salt together until the sugar has dissolved. Remove from the heat and allow to cool.
2. Once cooled, stir in the rest of the ingredients.
3. Serve the curry with the cucumber relish, jasmine rice, and lime wedges.