Process peas, water, cucumber, onion, mint, and sour cream in a blender until smooth. Stir in salt and pepper. Cover and chill 1 to 8 hours.
How to Blanch Peas: Cook desired amount of fresh sweet peas, snow peas, or sugar snap peas in boiling salted water to cover 1 to 3 minutes or until crisp-tender; drain. Plunge into ice-cold water to stop the cooking process; drain.