Line 2 baking sheets with parchment paper and set them on your work surface.

Put the 4 oz white chocolate (chopped) in a microwave-safe bowl. Heat in the microwave in 20-second intervals, stirring well between each interval, until the chocolate is fully melted and smooth.

While the white chocolate is melting, divide the peeled and segmented mandarin oranges into two roughly equal piles (one pile for white chocolate, one for dark chocolate).

Working with the pile for white chocolate, dip each mandarin segment so that about half of the segment is coated. Lift the segment and allow excess chocolate to drip back into the bowl. Place each dipped segment on the prepared parchment-lined baking sheet in a single layer, leaving a little space between pieces.

If using multi-color sprinkles, lightly sprinkle them onto the white chocolate-coated segments immediately after placing them on the sheet (before the chocolate begins to set).

Put the 4 oz dark or milk chocolate (chopped) in a separate microwave-safe bowl. Heat in the microwave in 20-second intervals, stirring well between each interval, until the chocolate is fully melted and smooth.

Dip each segment from the remaining pile into the dark chocolate, coating about half of each segment. Lift and let excess chocolate drip back into the bowl, then place the dipped segments on the second prepared parchment-lined baking sheet in a single layer.

If using coarse or flaked sea salt, lightly sprinkle it onto the dark chocolate-coated segments immediately after placing them on the sheet (before the chocolate begins to set).

Transfer both baking sheets to the refrigerator and chill until the chocolate is set, about 5–10 minutes.

Remove from the refrigerator and serve immediately for best texture and flavor.