Bring the water to a boil in a large pot. Add 1tablespoon salt and the vinegar, then add the shrimp. Cover the pot to bring the water back to a boil as quickly as possible. As soon as the shrimp are pink through and through, less than 1 minute after the water comes back to a boil, they are done. Drain them but do not rinse with cold water.
Finely chop enough parsley leaves to measure 1tablespoon. Shell the shrimp and devein. Put the shrimp and beans in a serving bowl. Season with salt. Add the parsley, olive oil, and lemon juice and toss well. Serve slightly warm or at room temperature.