Make the curry paste:
Place all ingredients and 1/2 cup of the coconut milk in a blender bowl. Blitz into a smooth paste, adding more coconut milk if needed to keep the blades moving.
Store in an airtight container in the freezer.
Make the Thai Yellow Curry:
Place 2 tbsp of the curry paste in a large saucepan, along with the coconut oil.
Heat together, stirring often, until the curry paste darkens slightly, about 2-3 minutes.
Add the onions and a pinch of salt and cook until they are translucent, 3-4 minutes.
Add basil, beans and vegetables and stir to mix well. Let the vegetables heat through.
Add the cashew paste along with enough water to thin out the curry to your liking. Let it heat through on a medium-low flame. Add the lemon juice.
Turn off the heat, garnish with spring onions, and serve hot.