Heat a little oil in a large frying pan or saucepan over medium heat. Add the onion and garlic and cook gently until softened.
Add the diced kūmara and potato. Cook for 3–4 minutes, stirring occasionally, to start the cooking process.
Stir in the Thai red curry paste and cook for 1–2 minutes until fragrant.
Pour in the coconut cream and 1 cup of water, stirring well to combine.
Add the chickpeas, brown sugar, salt and vegetable stock powder.
Bring to a gentle boil, then reduce the heat to a simmer. Cook for 15–20 minutes, stirring occasionally, until the potato and kūmara are tender.
In a small bowl, mix the cornflour with 2 Tbsp water until smooth. Pour the slurry into the curry while stirring and cook briefly until the sauce has thickened.
Add the spinach and stir through until just wilted.
Taste and adjust the seasoning or curry paste if needed, then serve hot.