In one bowl, whisk together the flour, baking powder, salt and baking soda.
In a separate bowl, whisk together the sour cream, both sugars, oil, egg and vanilla until very smooth.
Add the flour mixture to the sour cream mixture and fold together until the batter is almost smooth.
Add the chopped rhubarb and fold to incorporate throughout the batter.
Pour the batter into the prepared loaf pan and smooth the top.
Sprinkle the streusel evenly over the top of the bread.
Bake for 50 - 60 minutes, or until a tester inserted into the middle of the quick bread comes out clean. Allow to cool in pan for about 20 minutes before removing to finish cooling on a rack.