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.
Fold in the chopped rhubarb gently.
Divide the batter evenly among the muffin cups.
Bake for 20-25 minutes, or until a toothpick inserted into the center comes out clean.
Let the muffins cool in the tin for 5 minutes, then transfer to a wire rack to cool completely.