Prepare a bowl of ice water. Bring a large pot of water to a boil. Put the basil and parsley in a sieve and plunge it into the boiling water, pushing the leaves down into the water and stirring them so they blanch evenly. Blanch for 15 seconds, then plunge the herbs into the ice water to stop the cooking. Drain immediately, squeeze the herbs dry, and roughly chop.
In a blender, puree the herbs with the oil, pine nuts, garlic, salt, pepper, and ascorbic acid. When well blended, add the cheese and whir briefly just to mix. Transfer to a bowl and adjust the seasoning. Store the pesto in a small, covered container in the refrigerator for 1 to 2 weeks. Or freeze the pesto for as long as 1 month.
Note: I always toast pine nuts on a baking sheet in the oven. They tend to burn in a saute pan on the stove.
Recipe courtesy of Michael Chiarello