Preheat the oven to 375 degrees F. Grease a 12-cup muffin tin.
Grate the skin from the lemon (lemon zest) and squeeze the lemon, straining the seeds and saving the juice.
In a medium mixing bowl, combine the ½-cup sugar with the grated lemon zest. Use your fingers or a pastry blender to rub the zest into the sugar. Whisk in the flour, poppy seeds, baking powder and baking soda.
In a separate bowl, whisk together the butter, yogurt, eggs, lemon juice and vanilla.
Add the liquid ingredients to the dry ingredients, using a large spoon to stir until the flour mixture is fully incorporated.
Divide the batter evenly between the muffin cups. Sprinkle the tops with the coarse sugar. Bake until a toothpick comes out clean, about 15 to 18 minutes. Let muffins cool in the pan for 5 minutes, then transfer to a rack to cool completely.
"Maine Dish" columnist Cheryl Wixson lives and cooks in Stonington. Her passion for organic Maine products led to the creation of her business, Cheryl Wixson's Kitchen. She welcomes food-related questions and comments at [email protected] or www.cherylwixsonskitchen.com.