Preheat the oven to 325°F (165°C). Coat mini muffin pans with non-stick cooking spray and set them aside.

In a large bowl, combine the flour, sugar, salt, and baking soda, then set aside.

In a small saucepan, melt the butter over medium heat. Add the water and bring the mixture to a boil.

Pour the hot butter mixture over the dry ingredients, and blend gently with a hand mixer until just combined. Add the sour cream, egg, lemon zest, and lemon juice, and beat until the batter is smooth.

Fill the mini muffin pans with the batter. Bake in the preheated oven for approximately 12 minutes. Allow the cakes to cool in the pans for 5 minutes, then transfer them to wire racks to cool completely.

Once the cakes are fully cooled, dip them bottom side down into the prepared lemon glaze. Let any excess glaze drip back into the bowl, then place the cakes top side down onto the cooling racks. To make cleanup easier, place wax paper under the racks. Allow the glaze to harden completely.

In a small mixing bowl, whisk together the powdered sugar, lemon zest, melted butter, lemon juice, and milk until smooth.

Heat the glaze in the microwave for about 10 seconds to thin it out, if needed.