Place the vanilla extract and plant milk in a saucepan and bring to the boil. Remove from the heat and leave to infuse for 30 minutes.
In a separate bowl mix together the icing sugar, tapioca starch and agar agar. Add a few tablespoons of the milk to form a fluid paste and then whisk into the rest of the milk.
Add a drop of red food colouring at the point if you want to give the cream a light pink colour.
Put back on the heat and bring to the boil, whisking continuously until thickened. Reduce the heat to a low simmer and cook for 2 – 3 minutes, whisking continuously.
Take off the heat and pour it into a medium bowl. Cover with cling film to stop it forming a skin. Leave to one side and let cool to room temperature.
Weigh out the coconut oil and whisk for a few minutes until soft and creamy.
Once both the coconut oil and cooled milk mixture at roughly the same temperature, start to add them together gradually, whisking vigorously after each addition.
The coconut oil must emulsify completely with the thickened milk mixture. This step is essential to achieve a smooth mousseline cream!
It may separate as you mix it together but keep whisking vigorously and it will come together.
Once homogenised, cover the bowl with cling film and place in the fridge for a few hours or overnight to cool completely and firm up.