Preheat the oven to 350 degrees F and line a muffin pan.
Mix the sugar and lemon zest together in another bowl.
In a large mixing bowl, whisk together the egg, Greek yogurt, milk, lemon juice, avocado oil and vanilla extract.
Add the lemon sugar to the wet ingredients and mix until the sugar is dissolved.
Add the flour, baking powder, baking soda and salt into the bowl of wet ingredients and gently mix just until combined. Don’t overmix.
Add the poppy seeds and gently mix again.
Spoon the batter into the muffin pan filling ¾ of the way full.
Bake for 16-20 minutes or until a toothpick comes out clean.
To make the glaze mix together the powdered sugar and lemon juice, then use a spoon to drizzle the glaze onto the muffins. (Let the muffins cool before adding the glaze.)
