Preheat your oven to 375°F (190°C). Line a muffin tin with paper liners or grease it well.
In a large bowl, whisk together the flour, sugar, baking powder, baking soda, and salt.
In another bowl, mix the sour cream, vegetable oil, eggs, and vanilla extract until smooth.
Pour the wet ingredients into the dry ingredients and stir until just combined. Do not overmix.
Gently fold in the chopped rhubarb.
Divide the batter evenly among the muffin cups, filling each about ¾ full.
Bake for 20-25 minutes, or until a toothpick inserted into the center of a muffin comes out clean.
Allow the muffins to cool in the tin for 5 minutes, then transfer to a wire rack to cool completely.