How to Make It
Combine barbecue sauce, gochujang, rice vinegar, brown sugar, soy sauce, and grated ginger in a medium saucepan. Cook over medium, whisking occasionally, until slightly thickened, about 5 minutes. Remove from heat, and set aside.
Thread shishitos on 2 parallel skewers so that 1 skewer runs through each end of each pepper. Brush shishitos evenly with 1 tablespoon of the oil, and sprinkle evenly with 1/2 teaspoon of the salt. Rub chicken with remaining 2 tablespoons oil, and sprinkle with remaining 1 teaspoon salt. Insert 2 skewers in chicken, each running vertically between the drumstick and thigh, and breast and wing on each half of chicken.
Preheat grill to medium-high (about 450°F). Place chicken, skin side up, on oiled grill grate. Grill, covered, 10 minutes. Turn chicken; grill, covered, until a thermometer inserted in thickest portion of thigh registers 160°F. Brush skin side of chicken with 1/3 cup of the barbecue sauce mixture. Grill, skin side down, uncovered, until charred, about 2 minutes. Remove from grill, and let stand 10 minutes.
Grill shishitos and scallions, uncovered, turning occasionally, until charred, about 1 to 2 minutes for scallions and 4 minutes for shishitos.
Cut chicken into quarters. Serve chicken with grilled shishitos, scallions, and remaining barbecue sauce mixture. Garnish with lime wedges, cilantro, and pickled ginger.