Combine blood orange zest and juice in a small saucepan over medium heat. Stir in sugar until dissolved. Bring to a boil, stirring frequently. Reduce heat to low and simmer, stirring occasionally, until mixture thickens into a syrup, about 10 minutes. Remove from heat and let coulis cool, about 5 minutes.
Spread cooled coulis over toasted baguette slices. Spread foie gras on top.