How to Make It
Prepare an ice bath: Fill a large bowl with ice; fill bowl three-fourths full with cold water.
Prepare potatoes in microwave according to package directions, omitting seasoning from potatoes. Discard seasoning packet.
Plunge cooked potatoes into ice bath until completely cooled, about 1 minute. Remove to a colander with a slotted spoon; drain. Repeat procedure with haricots verts.
Cut potatoes into quarters; cut haricots verts in half crosswise. Toss together potatoes, haricots verts, shrimp, and corn in a large bowl. Stir together capers, lemon zest and juice, vinegar, Old Bay seasoning, salt, and pepper in a small bowl; whisk in oil until well combined.
Pour caper mixture over shrimp mixture; toss to coat. Stir in parsley, and serve immediately.