Pick through the hulled purple hull peas and discard any that are tough or immature.
Wash the purple hull peas in cool running water to remove soil.
Fill a large pot with water and bring it to a boil. While you wait for it to boil, fill a large bowl, to within two-thirds of the rim, with half ice and half water.
Place the purple hull peas into the boiling water, cover the pot and blanch for 90 seconds.
Pour the peas into a strainer, allowing the boiling water to drain, and then immediately plunge them into the ice water.
Pour cooled peas into the strainer and allow them to drain for two minutes.
Add the peas to a plastic freezer bag and seal it until it is almost closed. Insert a straw into the bag, suck out the air and quickly zip the bag until it is closed.
Place the bagged peas into the freezer immediately.