Preheat the oven to 425°F (220°C). Line a baking sheet with foil and set a wire rack on top if available.
Pat the wings dry with paper towels. In a large bowl, toss the wings with vegetable oil, salt, and black pepper until evenly coated.
Arrange the wings in a single layer on the prepared rack or baking sheet, leaving space between pieces. Roast for 20 minutes, turning once halfway through, until skin is crisp and internal temperature reaches 165°F (74°C).
While the wings roast, make the plum sauce: combine plum jam, soy sauce, rice vinegar, sriracha, grated ginger, and minced garlic in a small saucepan. Warm over medium-low heat, whisking until smooth and slightly thickened, about 3–5 minutes.
When wings are cooked, transfer them to a large bowl. Pour about three-quarters of the plum sauce over the wings and toss with tongs to coat evenly.
Return the sauced wings to the baking sheet and broil or roast for 2–4 minutes more to caramelize the glaze, watching closely to prevent burning.
Remove wings from the oven, brush with remaining sauce, and garnish with sesame seeds and sliced scallions if desired. Serve hot.