Add your sugar and water to a large saucepan. Turn the heat to medium, and stir until the sugar is completely dissolved in the water. Let it come to a light simmer, but not a rolling boil.
Once all sugar is dissolved, remove the syrup from the heat. Add in your borage leaves and let the borage steep into the syrup for 1 hour.
Strain and transfer your borage simple syrup to a sealed container in the refrigerator until it's ready to use.
Video
Notes
I use a nut milk bag to make sure I get all the petals out. It lasts longer without the petals in it.You can dry your own borage flowers fairly easily, but it takes a few harvests over a few days on one plant to yield the 1/2 cup for this recipe.Steep the borage in the simple syrup off the heat so it doesn't burn the flowers.