Begin with making the veloute. In a saucepan, heat the sunflower oil or 1 tablespoon of butter, add the onion and lemongrass then saute, without colour for a few minutes. Now add the minced ginger and garlic, cook on a low heat for a minute or 2, being careful not to burn the garlic. Now add the stock, bring to a rapid boil, then add the peas, bring back to the boil, then immediately remove from the heat and blend in a high speed blender. Once blended add the spinach, blanched mint and coconut milk, blend again until it’s really smooth. Pass through a sieve if you want it really smooth. Season to taste and chill quickly to keep the intense green colour if you’re not using it immediately. Otherwise pour into a saucepan, ready to heat.