Cook the rice with slightly salted water according to package instructions. Usually, it takes about 40-45 minutes until brown rice is cooked completely, therefore it’s good to start by cooking the rice before preparing the curry.
For the curry, wash the cauliflower head and cut it into small, bite-size florets. Discard the cauliflower leaves.
Peel the potatoes and cut them into bite-size pieces (similar size as the cauliflower florets).
Wash the zucchini, cut off and discard the ends, cut the zucchini lengthwise and proceed to cut into half moons.
Peel the onion, chop it finely and cook it with the coconut oil over medium heat until translucent.
Add the ground curry and cook for 1-2 minutes until the curry smells good.
Add the coconut milk and the tomato passata. Give it a good stir until the two liquids are well combined.
Add the cauliflower pieces, the potato pieces, the dried curry leaves, ground chili, lemon slices, sumach, and kaffir lime leaves. Stir and combine everything. Let it simmer over medium heat for about 10 minutes.
Add the zucchini pieces and continue cooking until the vegetables are starting to get soft (but don’t overcook, the cauliflower florets should still have a crunch).
When done, season with salt according to your taste.
Remove the lemon slices, and serve the curry with brown rice.
If you don't have zucchini, you can use other vegetables such as carrots. If using carrots, add them along with the cauliflower and potatoes.