Place 4 pounds chicken wings in the bottom of a 6-quart slow cooker in a single layer or in an even pile.
In a medium bowl, whisk 1/2 cup sriracha, 1/2 cup honey, 2 tablespoons soy sauce, 1/4 cup packed brown sugar, and 3 teaspoons minced garlic until smooth.
Pour the sauce evenly over the wings in the slow cooker.
Cover and cook on LOW for 3–4 hours or on HIGH for 1–2 hours, until the wings are cooked through and tender.
Carefully remove the wings from the slow cooker and place them on a foil-lined baking sheet.
Pour the cooking liquid from the slow cooker into a medium saucepan and bring to a simmer over medium-high heat.
In a small bowl, whisk 1 tablespoon cornstarch with 1 tablespoon water to make a slurry, then whisk the slurry into the simmering sauce and cook until the sauce thickens, about 1–2 minutes.
Baste the wings with the thickened sauce, then broil on high for 2–3 minutes until the tops are crispy and browned, watching carefully to prevent burning.
Return the sauced wings to the slow cooker or transfer to a serving platter and pour any remaining sauce over them.
Garnish with sliced green onions and sesame seeds and serve immediately.