1. Cut top and bottom off 3 oranges to expose flesh. Stand each orange upright, and cut off peel (including pith) in vertical strips. Cut flesh into 1/4-inch rounds, reserving juice in a bowl. Juice remaining 2 oranges, adding enough juice to reserved juice to equal 1/2 cup.

2. Make the caramel sauce: Prepare an ice-water bath. Bring sugar and 2 tablespoons water to a boil in a medium saucepan. Cook, stirring until sugar is dissolved; continue cooking until mixture is dark amber in color, about 6 minutes. Remove from heat, and slowly and carefully add butter, juice, and a pinch of salt, stirring until smooth (you should have 3/4 cup sauce). Transfer pan to ice-water bath, and let cool for 15 minutes.

3. Divide orange slices among 4 shallow bowls, and top with caramel sauce and cocoa nibs.