In a small sauté pan, lightly cook the garlic in 1/8-1/4 c. of the olive oil. Do not let the garlic brown, just soften; about one minute.
On medium-low speed, mix the egg yolk, lemon juice, vinegar, mustard, and salt until well blended and light yellow, about one minute.
With mixer on medium-low, slowly drizzle in the garlic and its cooking oil into the egg mixture. When the oil is completely mixed in, drizzle, one drop at a time, additional olive oil into the egg mixture. DO NOT add the oil too quickly; start with a drop at a time and as the aioli gets lighter in color and thicker, you can increase to a very fine stream.
Alternate between olive and your other oil, tasting after you’ve added about 1/2 cup total oil and adjusting proportions for your final oil additions, adding the final amount of oil to taste.
If you have an immversion blender with a whisk attachment, it works better than a stand mixer when used in a small bowl... Just don't go quite so slow as described above or your aioli will be too fluffy and not so creamy.
Goes great with our oven fries recipe!