In a saucepan, combine 1 1/2 cups of the sugar and the water and bring to a boil over high heat, stirring constantly, until the sugar has dissolved completely, about 5 minutes.
Reduce the heat to low, add the blood orange slices, and simmer until translucent, about 20 -30 minutes. Remove the pan from the heat and let cool completely, about 2 hours in a cool spot.
Place waxed paper over a sheet pan. Using tongs, remove the slices, shaking off any excess syrup. Place on the rack in a single layer. Let the slices dry overnight. Reserve the syrup for another use (we used it to for our afternoon tea.)
Line a baking sheet with parchment paper. Put the chocolate in a heatproof bowl placed over simmering water in a saucepan. Melt the chocolate, stirring until smooth. Remove from the heat.
Dip each candied blood orange slice halfway into the chocolate and then place on the parchment in a single layer. Leave until the chocolate has set, about 1 hour. Garnish with Maldon salt.