Place egg, lemon juice and salt in blender or food processor and start running on low.

Once mixed slowly start dripping your oil in

I drip 1 tbsp of oil at a time and let it mix for at least a minute

As you continue to add your oil, it will emulsify but continue to add slowly so you don't break it

Once your mayonnaise is done, then you can hand mix in any optional ingredients you want

Store in an airtight container in the refrigerator for up to a week

Invest in an immersion blender so you can make the mayo faster like above