Heat grill to medium-high. Once it is hot, clean the grill grate with a wire brush. Just before grilling, oil the grill grate.
Season the steaks with the seafood seasoning and ¼ teaspoon each salt and pepper. Brush the corn and onion with 2 tablespoons of the oil and season with ¼ teaspoon each salt and pepper.
Grill until an instant-read thermometer inserted into the center of each steak registers 130°F, 3 to 4 minutes per side for medium-rare. Grill the corn and onion, turning occasionally, until tender, 5 to 7 minutes. Let the steak rest 5 minutes before slicing.
Cut the kernels off the cobs and combine with the onion, black-eyed peas, chives, vinegar, and the remaining tablespoon of oil, in a medium bowl. Serve with the steak.