Boil 1 cup of water in a small pot. Add the tarragon leaves, and cook for 5 seconds, until bright green. Plunge in a bowl of ice water to immediately cool.
Drain, press ALL the water from the herb and dry.
Make vinaigrette: In a blender, place the next eight ingredients, garlic cloves through scallions. Blend well to combine.
Add the dry, blanched tarragon and blend until smooth and bright green. No rush here, just leave the blender whirling until it is done.
Pour the canola oil in a measuring cup, turn the blender on and drizzle the oil in – slowly to emulsify.
Finish by drizzling in the olive oil.
Store in an airtight container (preferably glass) in the refrigerator.