Mix soy milk and lemon juice
Let it sit for 2 full minutes
This will allow them to mix together
Next stick in your immersion blender and run it for a full 30 seconds without lifting it
Then slowly add in the oil while running the blender, Add in the mustard and black pepper and continue to blend for further 10 seconds
Move blender up and down to check the desired thickness and continue to blend for another 30 seconds until you achieved the desired level of thickness
Store in fridge overnight
The mayonnaise should thicken further well
Stays fresh for up to a week