1. Make the pickling liquid: In a container large enough for shrimp, combine all pickling ingredients and set aside.
2. Make the shrimp: Add lemon slices and Old Bay to a large pot of water. Add shrimp and simmer (but not boil) until firm but not quite cooked through. Remove shrimp, arrange in a single layer on a rimmed baking sheet, and set aside in refrigerator to cool completely.
3. Once shrimp are cooled, peel and transfer to pickling liquid. Set aside in refrigerator for at least 6 hours or overnight.
4. Make the salad: Drain shrimp, reserving liquid, and chop. In a large bowl, combine beans, radish, and 1⁄3 of shrimp (reserve the rest for another use). Coat generously with pickled shrimp liquid. Add herbs and gently toss.