Combine egg yolks, salt, garlic and the mustard in a large mixing bowl.
Using an electric mixer, start whisking the mixture on a medium spin setting in one continuous direction for about 30 seconds or until mixed throughout.
Whilst still whisking the mixture, add 20-50ml of oil.
Once mixed throughout, continue the above process, gradually adding 20-50ml oil at a time until all oil is finished.
The desired texture should be creamy yet stable, should it break down then repeat with one egg yolk and broken-down mixture in replacement of oil.
Store in airtight jar and keep refrigerated for up to a week.