Slice the leeks into thick rings about 1.5 cm thick, rinse thoroughly under cold water to remove any dirt trapped between layers, then set aside.
Peel the potatoes and dice them into uniform 2 cm cubes, ensuring they cook evenly and become tender in the simmering process.
Heat the oil in a large heavy-bottomed pan over medium heat until shimmering and fragrant. Add the sliced leeks and a pinch of salt, cooking gently for about 8 minutes until they turn translucent and begin to caramelize slightly, filling the kitchen with a sweet aroma.
Stir in the cumin seeds and turmeric, toasting them in the oil for about 30 seconds until fragrant and golden, which enhances their aroma and deepens the flavor.
Add the diced potatoes to the pan, stirring well to coat them in the spices and leeks. Cook for a couple of minutes until they start to develop a slight glaze and absorb the flavors.
Pour in the coconut milk and water, stirring gently to combine. Bring the mixture to a gentle simmer, then reduce the heat to low. Cover loosely with a lid and let it cook for 20-25 minutes, stirring occasionally, until the potatoes are tender and the curry has thickened with a rich, golden hue.
Once the potatoes are soft and the curry is thickened, taste and season with salt. Add a squeeze of lemon or lime to brighten the flavors, and let it rest off the heat for 5 minutes to allow the flavors to meld.
Garnish with chopped cilantro or parsley just before serving. Serve hot with rice or warm naan for a cozy, satisfying meal.
