Preheat oven to 350°F. Grease a 9x5" loaf pan and set aside.
In a medium bowl, mix the flour, baking soda, ginger, cinnamon, and salt together. Set aside. In a separate, smaller bowl, mix the molasses and hot water until combined.
Using a hand mixer or a stand mixer fitted with the paddle attachment, cream the butter with the brown sugar. Add the sour cream and vanilla extract and beat until combined.
Add the dry ingredients into the wet ingredients in thirds, alternating with the molasses, making sure to start and end with the dry ingredients. Beat after each addition.
Pour the batter into prepared loaf pan and bake 45-50 minutes, or until a toothpick inserted into the center comes out clean. Cool completely before removing from the pan.