1. Bring 8 cups water to a boil in a large Dutch oven. Add peas; cook 30 seconds or until crisp-tender. Drain and plunge into ice water; drain. Slice half of peas diagonally.
2. Combine lemon rind and next 7 ingredients in a medium bowl; stir with a whisk. Add peas; toss to coat.
3. Add radishes, crumbled feta, and chopped fresh mint to pea mixture. Toss to combine.