In a heavy skillet, heat the 2 teaspoons of the oil over medium heat. Add onion and saute for 5 minutes until soft and tender.Scrape onion into a medium bowl and let cool for 5 minutes. Add chicken, mango, chives, red pepper flakes and salt. Using clean hands, mix everything together, making sure to get the mango distributed throughout.Using wet hands, form the chicken into 8 equal sized patties, pushing down to flatten a little bit and laying on parchment paper.Heat the same skillet over medium high heat and add remaining oil. Gently place patties in the pan, in batches if needed for about 3-4 minutes on each side, until golden brown on each side and cooked through.