Preparation

• In a medium bowl or large zip-top bag, combine the soy sauce, sugar, vinegar, sesame oil, sambal oelek, ginger, and garlic. reserve 1/4 cup of the marinade. Add the thighs to the remaining marinade and turn to coat. Let sit at room temperature for a half-hour, turning once, or refrigerate covered for up to 2 hours, turning the thighs occasionally.
• Cut 11 of the scallions into 1-inch pieces. Thinly slice the remaining scallion on the bias and reserve separately.
• Heat 1 Tbs. of the vegetable oil in a large skillet over medium-high heat until shimmering. Add the 11 scallions and cook, stirring, until fragrant, about 10 seconds. Add the reserved 1/4 cup marinade to the pan and cook, stirring frequently, until the scallions are slightly charred and the sauce has thickened, about 2-1/2 minutes. Remove from the pan and set aside.
• Add the remaining 1 Tbs. of vegetable oil to the pan. Add the thighs to the skillet smooth side down without patting them dry. Cook undisturbed, adjusting the heat as necessary, until browned, 6 to 7 minutes. Shake the pan to loosen the thighs, flip, lower the heat to medium, and cook until done (cut into a thigh at the thickest part to check), another 7 to 8 minutes. Return the cooked scallions to the pan and toss. Serve the chicken garnished with the scallion slices.