Cut the unpeeled sweet potato into 2cm chunks. Crush or finely chop 2 garlic cloves. Cut the fish into 3cm chunks.
Step 2 — Start soup
Put the curry powder, garlic and 2 tsp vegetable oil in a medium saucepan over medium-high heat. Cook, stirring, for 30 secs to infuse the oil. Add the sweet potato, coconut milk and 300ml water and bring to the boil. Reduce the heat to medium-low and simmer, stirring occasionally, for 10 mins or until the sweet potato is just tender.
Step 3 — Toast coconut
Meanwhile, put the coconut in a cold small frypan over medium heat. Toast, tossing, for 2-3 mins until evenly golden. Remove from the pan.
Step 4 — Finish soup
Add the fish to the soup and cook, stirring occasionally, for 4-5 mins until the fish is cooked through. Add the spinach, 1½ tsp soy sauce and 1 tsp white vinegar and stir for 1 min or until the spinach is wilted. Remove the pan from the heat. Taste, then season with salt and pepper.
Step 5 — Serve up
Divide the soup among bowls, scatter with the toasted coconut and enjoy!
Step 6 — Did you know?
A type of curry powder, vadouvan (pronounced vah-doo-vahn) originated in the French colonised area of Pondicherry in southeast India. It's milder and slightly sweeter than most Indian curry powders.