Raw Food. Better than Hellman's Mayonnaise

Make this mayonnaise using a food processor if you have one. If not, use an electric hand blender. If you don't have an electric hand blender, roll up your sleeves and get beating!

Put in a large bowl (or processing container):

1 egg
1 teaspoon dry mustard (or else 1 teaspoon prepared English mustard/2-3 teaspoons Dijon mustard but which you should add as flavouring at the end)
1/2 teaspoon salt
1 teaspoon sugar
1/4 cup olive oil (if you don't have a cup measure, use a standard mug for which 1 mug=1cup)

Blend until thoroughly combined.
Whilst the blender is still running, very, very slowly add:

1/2 cup / 1/2 mug olive oil

And then:

The juice of 1 lemon.

Keep blending. Then very, very slowly add another:

1/2 cup / 1/2 mug olive oil.

Blend until thick and creamy. You may have to start and stop the blender to stir down the mayonnaise.