Wash and thoroughly dry the oranges. Using a sharp knife, slice off both ends of the oranges. Stand each orange upright and carefully slice into 1/4-inch thick rounds.

Lay the orange slices on paper towels and gently blot both sides to remove as much excess moisture as possible. This step is crucial for the chocolate to adhere properly. Set aside.

Line a baking sheet with parchment paper and set aside.

Set up a double boiler: Fill a medium saucepan with about 1-2 inches of water and bring to a gentle simmer over medium heat. Place a heatproof bowl (glass or stainless steel) on top, ensuring the bottom of the bowl does not touch the water. Add the chopped dark chocolate and coconut oil (if using) to the bowl. Stir occasionally until the chocolate is completely melted and smooth. Alternatively, melt the chocolate in a microwave-safe bowl in 30-second intervals, stirring after each, until smooth.

Carefully remove the bowl from the heat. Let the chocolate cool for a minute or two, stirring, to ensure it's not too hot.

Dip each orange slice halfway into the melted chocolate, allowing any excess chocolate to drip off back into the bowl. You can use a fork to help lift them out if needed.

Place the dipped orange slices onto the prepared baking sheet.

Immediately sprinkle the chocolate-dipped sections with flaky sea salt and any other desired optional garnishes (orange zest, chopped pistachios, shredded coconut) before the chocolate sets.

Transfer the baking sheet to the refrigerator and chill for at least 30 minutes, or until the chocolate is completely set and firm to the touch.

Once chilled and the chocolate is firm, arrange the Chocolate Dipped Oranges on a platter and serve immediately.