Place 1 pound chopped rhubarb in a glass 9 x 13-inch baking pan. In a small bowl, whisk together 1/2 cup granulated sugar, 1/4 cup fresh blood orange juice, and zest from 1 blood orange — don't worry if the sugar doesn't dissolve, you should end up with a thick, grainy syrup. Drizzle over the rhubarb and use a rubber spatula, tossing the fruit until all the rhubarb pieces are covered in syrup.