Starting with all ingredients at room temperature.

In blender add egg, salt, mustard powder and about 1/4 cup of oil and blend well.

With blender still going, remove the small cap in the center of the top. Then SLOWLY add in the rest of the oil while blending.

After you have mixed all the oil in and have reached a mayo texture, stir in lemon juice.

Place in an airtight container and put in the fridge.