Press the silken tofu for 5-10 minutes. This is an important step as it will extract about ½ cup water and prevent your mayo from being watery.
Put the pressed tofu into a bowl with the vinegar, lemon juice, mustard and salt. Whizz together with a hand blender or whisk and when combined, gradually add the oil, a little at a time until you reach the desired consistancy. And that is it. Store in a clean jar in the fridge, it will keep in the fridge for up to 5 days.