Chop the dark chocolate finely and place it in a heatproof bowl.

In a saucepan, heat the heavy cream over medium heat until it just begins to simmer, then remove from heat.

Pour the hot cream over the chopped chocolate and let it sit for a minute before stirring.

Add the orange zest, orange juice, sugar, vanilla extract, and sea salt to the chocolate mixture and stir well until combined.

Cover the bowl and refrigerate the mixture for about 2 hours or until firm enough to shape.

Once the mixture is firm, use a melon baller or small spoon to scoop out portions and roll them into balls.

Roll each truffle in cocoa powder until fully coated.

Place the finished truffles on a parchment-lined tray and refrigerate until serving.