1. Preheat oven to 375°F (190°C) and line a 12 cup muffin tin with paper liners or grease each cup.

2. In a large bowl whisk together sourdough discard, eggs, sugar, melted butter, milk, lemon juice, and lemon zest until smooth.

3. In a separate bowl sift together flour, baking powder, baking soda, salt, and poppy seeds.

4. Pour the dry ingredients into the wet ingredients and fold gently with a spatula until just combined, avoiding overmixing.

5. Let the batter rest for 10 to 15 minutes to hydrate the flour and develop texture.

6. Fill each muffin cup about three quarters full and sprinkle coarse sugar on top if desired.

7. Bake for 18 to 22 minutes or until the tops are golden and a toothpick inserted in the center comes out clean.

8. Allow muffins to cool in the pan for 5 minutes then transfer to a wire rack to cool completely before glazing.

9. For the glaze whisk 1/2 cup powdered sugar, 1 to 2 tablespoons fresh lemon juice, and 1/2 teaspoon lemon zest until smooth.

10. Drizzle or dip cooled muffins in the glaze and sprinkle with extra poppy seeds or lemon zest before the glaze sets.