How to Make It
Zest and juice 4 of the 5 oranges. Cut the remaining 1 orange into thin rounds; slice the rounds in half and set aside (for garnish).
Combine the orange zest, juice, sugar, and water in a small saucepan over medium heat. Bring to a boil. Remove pan from heat and let stand for 10 minutes.
Strain orange mixture. Stir in both bitters; cover and chill for about 20 minutes.
Combine ¾ cup of LaCroix with 2 tablespoons of blood orange mixture, or to taste; pour over ice and garnish with orange slices.