Zest the lime and squeeze out the juice. Scrape the vanilla bean. In a large bowl, whisk the egg whites, lime zest and juice, sugar, vanilla extract, and salt using a hand mixer with beaters. Stir in the shredded coconut. Cover with plastic wrap and let rest in the fridge for about 1 hour.
Preheat the oven to 165°C convection (or 185°C top/bottom heat). Line a baking sheet with parchment paper. Use an ice cream scoop or spoon to form about 20 small, loose cones of coconut mixture and place them on the baking sheet. Bake in the middle of the oven for about 10-15 minutes. The macaroons should be lightly browned but still a bit soft. Remove from the oven and let cool completely. Only remove from the parchment paper once fully cooled.
Roughly chop the chocolate and melt it in a bowl over a water bath. Dip the flat side of the macaroons into the melted chocolate and place them back onto the parchment paper. Alternatively, place some melted chocolate on the parchment paper and press the flat side of the macaroons into it to cool. Decorate with the remaining chocolate if desired.
