Start by adding aquafaba, agave nectar, lemon juice, salt, and mustard to a tall cup. Using the immersion blender, give the mixture a few quick pulses to combine everything and froth it up a bit.

While blending, slowing pour oil in, about ¼ cup at a time. It's important to add the oil in slowly! The emulsification process takes time, so be patient, it will come together.

As you add more oil, the eggless mayo will begin to thicken up. Once the mayo emulsifies, move the immersion blender up and down to ensure everything is combined and creamy.