In a medium bowl, combine sugar and sorghum syrup. Rub syrup into sugar with your fingertips until evenly incorporated. (It will look like golden light brown sugar.) Add flour, butter, and salt, and rub together with your fingertips until large clumps form. Freeze until ready to use, up to 1 day.
Recipe by Bake from Scratch at https://www.bakefromscratch.com/roasted-pecan-pound-cake-sorghum-streusel/