Heat a splash of olive oil in a pot over medium heat. Add the chopped onion and sauté until softened and fragrant.
Stir in the curry powder, dried coriander, and turmeric, letting the spices toast for a minute until aromatic.
Add the brown sugar and stir to combine, allowing the mixture to develop a rich, fragrant base.
Add the chopped potatoes and pumpkin, ensuring the pieces are cut roughly the same size so they cook evenly. Stir to coat the vegetables thoroughly in the spice mixture, letting them absorb the flavours.
Pour in the coconut milk and vegetable stock, ensuring the liquid covers about halfway up the vegetables.
Stir everything together, then add the soy sauce for extra depth of flavour.
Cover the pot with a lid and let the curry simmer over low heat for about 25 to 30 minutes, stirring occasionally. As the vegetables cook, they will soften, and the sauce will thicken naturally. The pumpkin will start to break down slightly, adding body to the sauce while the potatoes remain hearty.
Once the vegetables are tender, remove the lid and give everything a final stir. Taste and adjust seasoning if needed. Serve hot, garnished with fresh coriander.