Made Mayo with an immersion blender in a jar - used a classic 1 egg, 1 cup oil, 1 tbsp lemon juice, 1 tsp mustard ratio. Even after several rounds of blending the taste is distinctly oily - should I add more lemon/salt/mustard?
You could substitute vinegar for the lemon. The acetic acid is stronger and rounds up the fatty taste more effectively. 1 1/2 - 2 tsps. Also, you could easily reduce the oil to 3/4 cups.
Agree with Droplet.
Have successfully made mayo with less than 1c oil: start checking at 3/4c, and only add more oil as taste & texture demand.
Meanwhile, for this batch, in addition to the vinegar, serve it with more sour things - citrus, pickles etc - and when using it in a prepared dish, don't add more fat (butter, meat drippings, etc) to avoid emphasizing the oily part of the sauce.
Try beating in another egg yolk.
I agree with all the above. And next time, check for taste as you drizzle in the oil.
I would also add a dash of Tabasco.