Wet a kitchen towel and wring out until just damp. Shape the towel into a ring on the counter and nestle a medium bowl in the center. Place the oil in a measuring cup with a spout and set aside.

Finely grate the garlic into the bowl. Add the kosher salt and egg yolk. Whisk briefly to combine.

Whisk the egg yolk mixture briefly, then add olive oil a few drops at a time while whisking continuously. As the aioli begins to emulsify, increase the oil to a steady, thin stream while whisking continuously.

Once all oil has been added, whisk a few more times to ensure thorough emulsification. Whisk in lemon juice. Taste for salt and adjust if necessary.