Preheat the oven to 425°F (220°C). Spray a 6-cup muffin pan with nonstick spray or line it with cupcake liners, then set it aside.
Add the granulated sugar to a large bowl and, using your fingers, rub the lemon zest into the sugar until it’s well combined, fragrant, and the sugar has a yellow hue to it.
Add the oil, egg, Greek yogurt, sour cream, milk, and lemon juice, and whisk until the sugar is dissolved and no lumps from the yogurt and sour cream remain, about 2 to 3 minutes. Set aside.
In a separate large bowl, whisk together the flour, baking powder, baking soda, salt, and poppy seeds. Pour the wet ingredients into the dry ingredients, then fold everything together gently until just combined.
Spoon the batter into the prepared muffin pan, filling each cup to the top; you’ll use 4½ tablespoons of batter per cup.
Bake the muffins for 5 minutes. Keeping the muffins in the oven, reduce the oven temperature to 350°F (180°C), and bake them for 15 to 17 minutes, or until a toothpick inserted into the center comes out clean. Allow the muffins to cool for 10 minutes in the pan before removing them to a wire rack to cool completely.