How to Make It
In a small saucepan, bring the vinegar to a boil with the salt, sugar and pepper. Cook over high heat until the salt and sugar dissolve, about 2 minutes. Remove from heat, stir in the onion slices, and let the onion pickle stand at room temperature for 1 hour.
Light a grill. In a large bowl, mix the Old Bay, Cajun spice, smoked paprika, rosemary, cayenne and 1 tablespoon of the olive oil. Add the shrimp and toss well. Grill the shrimp over high heat, turning once, until the shrimp are lightly charred and white throughout, about 2 minutes.
Rub the corn with the butter and season with salt and black pepper. Grill over moderately high heat, turning occasionally, until the kernels are charred and tender, about 10 minutes. Let the ears cool slightly.
Using a serrated knife, cut the kernels from the ears over a large bowl. Toss the corn with the cucumbers, dates, cilantro, lime juice and the remaining 1 tablespoon of olive oil. Drain the pickled onion strips and add them to the salad. Season with salt and pepper and toss well. Transfer to a platter, top with the grilled shrimp, garnish with the pea shoots and serve.