Homemade curry paste
Prepare the curry paste (or use store-bought). Lightly crush the lemongrass with a side of a large knife to release some aromatic oils, then remove the root end and discard the outer layers. Chop the inner layer of lemongrass and put it into a pestle and mortar. Peel and dice the onion and garlic, then add to the pestle and mortar with the the coriander seeds, sweet paprika, turmeric, cumin, fresh coriander, chopped chili and peanuts. Grind until fine.
Place a small frying pan over medium high heat. Add in the curry paste and fry for about 2 - 3 minutes (it will smell fantastic) then transfer to a small bowl.
Cook the onions
Heat 2 tablespoons of oil in a large saucepan over a medium-high heat. Add the chopped onions, chopped garlic and homemade curry paste. Cook for about 5 minutes, stirring occasionally.
Add the rest of the vegetables
Chop the potato and sweet potatoes into small chunks. Slice the leek. Add to the onions. Drain and tip in the chickpeas (or use canned), then cook for 5 minutes, stir occasionally.
Stir in the coconut milk and 300 ml water. Cover with a lid and cook for 40 minutes on low heat.
Season to taste
Season to taste with salt and pepper. Add in the zest and juice of one lime.
Serve Sweet Potato and Chickpeas Curry with basmati rice. Scatter over the coriander leaves, and add coconut flakes, peanuts and lime wedges, if you like. Enjoy.
Store the cooled curry in an airtight container in the fridge for 2 days. Store the cooled homemade curry paste in an airtight container in the fridge for up to a week or freeze for up to a month.