1. Place sliced red onions into a large mixing bowl.
2. Boil water and pour over sliced red onions. Fully cover the red onion slices in boiling water for 10 seconds, then drain.
3. Transfer the drained red onion slices into a large Mason jar.
4. Mix the Florida Orange Juice, lime juice, sugar and salt together in a separate bowl.
5. Pour the mixture over the red onions and let sit, covered, for at least 4 hours.