Make the batter: Mash the bananas in the bottom of a large bowl, enough for 1 1/4 cups. Whisk in the oil, sugar, eggs, sour cream, and vanilla extract.
In a separate bowl, mix the flour, baking soda, cinnamon, ginger and kosher salt. Pour the wet ingredients into the dry ingredients and gently stir together with a spatula until just combined.
Bake: Pour the batter into the loaf pan and top with the turbinado sugar. Bake about 55 minutes, until a toothpick inserted into the center of the loaf comes out clean (or the internal temperature is 200 degrees): the exact timing will depend on the size of the pan.
Cool: Cool in the pan for 15 minutes. Then run a knife around the edge and invert the loaf onto a cooling rack. Serve warm or at room temperature. Storage info: The bread lasts 4 to 5 days at room temperature wrapped in aluminum foil, refrigerated for 10 days, or frozen for 3 months (slice it into pieces and wrap it in plastic wrap then a freezer-safe bag or container).