Muffins:
2/3 cup granulated sugar
zest and juice of 1 lemon
2 cups all-purpose flour
2 teaspoons baking powder
1/4 teaspoon baking soda
1/4 teaspoon salt
3/4 cup buttermilk or sour cream
2 large eggs
1 teaspoon vanilla extract
1 stick (8 Tablespoons) butter, melted until browned and cooled
2 Tablespoons poppy seeds
2 Tablespoons granulated sugar (for topping the batter before baking)

Glaze:
1 cup powdered sugar whisked together with 2 or 3 Tablespoons of lemon juice