Peel and slice the mango into thin strips (matchstick style). If using green mango, peel first and cut into sticks.
Cut the cabbage, cucumber, carrot, and onion into thin slices. Keep them crisp.
In a small bowl, whisk lime juice, fish sauce (or soy sauce), sugar, garlic, chili, and sesame oil until the sugar dissolves.
Add the mango, vegetables, cilantro, and mint to a large mixing bowl. Pour the dressing on top.
Gently toss everything together until evenly coated.
Sprinkle with chopped roasted peanuts before serving.