Using a vegetable peeler or zester, remove the zest of the orange, taking care to leave the pith behind.
In a small saucepan over medium heat whisk together the sugar with 1/4 cup water and the orange zest. Bring to a simmer and remove from heat. Cool to room temperature.
Reserve 4 strawberries for garnish and remove the hulls and roughly chop the remainder. Add the strawberries with the juice of the orange to a blender and fill with ice. Add the cooled orange simple syrup and blend until smooth. Add the rum, if desired, and blend. Pour into glasses and garnish with reserved strawberries.
Recipe courtesy of Sandra Lee