Heat 2-3 tablespoons of oil in a large pot over medium heat.
Add the onion and sauté for about 5 minutes, until softened and translucent.
Add the minced garlic and grated ginger, and cook for another 2-3 minutes, until fragrant.
Stir in the red curry paste and tomato paste, cooking for 2-3 minutes to release their flavours.
Add the sweet potatoes, chickpeas, vegetable stock, coconut milk and chilli flakes. Stir until combined then mix in the peanut butter.
Bring to a simmer (uncovered) for 15-20 minutes, or until the sweet potatoes are just cooked through.
Stir in fish sauce, lime juice and sweet potato leaves, until wilted, then serve with coriander and chilli oil.
