In a large skillet, heat the oil over medium-high heat. Add the ginger and cook until fragrant, 30 seconds.
Add the bell pepper, broccoli, and scallions and cook, tossing often, until the broccoli is crisp-tender, 3 to 5 minutes.
Add the hoisin sauce and ¼ cup water and cook, tossing, until tender, 2 to 3 minutes. Sprinkle with the sesame seeds.