In a blender or food processor, add the egg yolk, egg and mustard and set aside. Let these ingredients meld for about 10 minutes.
Peel and chop the garlic very fine. Sprinkle 1/2 teaspoon salt over the garlic and, using the back of your knife, crush it all together so it becomes almost like a paste.
To the blender or food processor, add 2 teaspoons lemon juice with the egg and mustard mixture.
Now, here is the trick. I used a 1/4 cup size measuring cup so I would be cognizant of drizzling the oil slowly. And the 1/4 cup fit just inside the removable top to the blender so I could use this also to minimize the splashing effect.
Fill the 1/4 cup with grapeseed oil and turn on the blender. Drizzle e-s-l-o-w-l-y. Just keep a thin line of oil drizzling in at all time. This will take at least a minute to drizzle each 1/4 cup. Then fill the 1/4 cup with oil three more times and drizzle slowly...leaving the blender or food processor running the entire time.
Before long, you will have a gorgeous mayonnaise. Add the garlic-salt paste, black pepper and 2 tablespoons lemon juice and blend until smooth.
For the best tasting aioli, store in an air-tight container in the refrigerator.