Preheat your oven to 425°F
Combine the first two ingredients, sugar and lemon zest, in a small bowl and set aside.
Combine flour, baking powder, salt, and 1 tbsp sugar in mixing bowl.
Cut your butter into small cubes, about 1 cm cubed and mix with the flour mixture. if the butter is too large go ahead and break them apart with your fingers, but don't handle the butter too much, you want it to stay cold.
Mix the buttermilk into the wet ingredients, be careful not to overmix! You should still see chunks of butter and the dough should just come together.
Turn out the dough on your work surface and, using your hands, flatten out into a square or rectangle shape about 1 inch thick.
Cut your dough into 4 equal pieces and place on a lined baking sheet so that the edges are just barely touching each other.
Take your lemon sugar and separate evenly on the four biscuits, packing it on with your hand so it is evenly spread and tightly packed.
Bake your biscuits for 11-15 minutes until golden brown. Cool on the sheet pan you baked them on, the butter will soak back into the cooked biscuits.