Slowly add the dry ingredients to the sourdough mixture. Gently combine, being careful not to overmix.
Spoon the batter evenly into the prepared muffin tin.
Bake for 20 minutes or until a toothpick or cake tester comes out clean from the center of a muffin. The edges should turn golden brown.
Remove from the oven and place on a wire rack to cool.
Make the glaze:
Combine powdered sugar and lemon juice in a small bowl until combined. Drizzle icing mixture over your muffins with a spoon or add it to a ziplock bag and cut the corner.
113 grams powdered sugar, 2 tablespoons lemon juice