Preheat your oven to 350°F (175°C). Roast the duck breast for 20-25 minutes, or until fully cooked. Let rest and slice thinly., Boil the sweet potatoes until soft, then mash them in a bowl., Steam or lightly warm the blueberries., Mix the sliced duck with the mashed sweet potatoes and blueberries. Add chia seeds if desired., Let the mixture cool before serving. Store leftovers in the fridge for up to 3 days.