1 Put the oil, milk powder and water into the blender.
2 Blend at a low speed until well mixed. Add salt, pepper, mustard, lime juice and sugar.
3 Blend at high speed till the mayonnaise is thick and smooth. Finally fold in the cream, if using.
4 Use straight away or store in an airtight jar in the refrigerator.
If you find it thin, add more milk powder; if too thick, add a little hot water. If you add the lime juice at the beginning, you'll find the mayonnaise emulsify faster.