Take washed spinach leaves and put them into water.
Boil 2 minutes.
Remove from the heat and let cool completely.
Put in a blender jar, alongwith its water and blend to a fine puree.
Sieve through a fine masher.
Pour the extracted juice in a sauce pan.
Also add sugar.
Boil on high heat while stirring occasionally.
A foam will be seen forming over the top layer. Remove it as much as you can.
When the syrup reduces and appears like bubbles, check the consistency by taking a drop out and pulling apart between your forefinger and thumb. It should be one string consistency.
Add lemon juice and just one boil.
Switch off the heat and add vanilla essence. Mix.
Sieve in a bowl.
Leave to cool completely and thereafter fill in a bottle. This is the green. food colour.