Take cornflour in a bowl, add in ½ cup of milk and mix well.
Now take remaining milk in a sauce pan and heat till it is heated up.
Add in the cornflour mix in slowly and keep mixing till there is no lumps. Keep cooking till it gets thick.
Remove this to a bowl, add in remaining ingredients and use a whisk to whip till creamy.
Refrigerate it and use as needed.
Notes
1)When you refrigerate it, if it gets too thick. take the mayo in a mixer, add little more milk and blend till smooth.
2)This can be stored in fridge for 10 days.