Combine rice vinegar, sugar, and sesame oil in a small saucepan and bring to a boil over medium heat. Reduce heat to simmer for 2 minutes to allow the sugar to dissolve. Leave mixture to cool to room temperature.
Add cucumber, onion and chili pepper to a mixing bowl and pour over the cooled vinegar solution. Stir to mix everything together. Tightly cover bowl with Reynolds Wrap® Aluminum Foil and place in fridge for 30 minutes.
Preheat oven to 350 degrees F and line a baking sheet with Reynolds Kitchens® Parchment Paper. Place peanuts on baking sheet and season with a generous pinch of salt. Roast for 30 minutes, rotating the pan halfway through.
Remove the cucumber mixture from fridge and transfer to serving dish. Top with bean sprouts and roasted peanuts. Serve with lime wedges.