01 -  Preheat oven to 350°F (175°C). Grease and flour a 9×5-inch loaf pan or line with parchment paper. 
 02 -  In a medium bowl, whisk together flour, baking soda, baking powder, salt, and cinnamon until well combined. 
 03 -  In a large bowl, beat together oil, sugar, sour cream, egg, and vanilla until smooth and fully incorporated. 
 04 -  Gradually stir the dry ingredients into the wet mixture until just combined. Gently fold in the chopped rhubarb. 
 05 -  Pour batter into the prepared loaf pan. Sprinkle with cinnamon sugar or streusel topping if desired. 
 06 -  Bake for 50–60 minutes, or until a toothpick inserted in the center comes out clean. 
 07 -  Let cool in the pan for 10 minutes, then transfer to a wire rack to cool completely before slicing.