Blanch the basil - Dip the basil into boiling water for 30 seconds, then plunge it into an ice water bath to stop the cooking and preserve the bright green color. Let it drain while you prep the other ingredients, and gently pat the basil dry before adding it to the blender.
Prep ingredients - Mince the garlic and shallot. Squeeze the lemon.
Blend - Add the basil, garlic, shallot, 2 t lemon juice (reserving the remainder for another purpose), vinegar, salt, and oil to your blender jar. Blend until smooth.
Notes
This vinaigrette will last for a few days in your fridge.