01 -
Preheat oven to 350F and line a 12-cup muffin pan with paper muffin liners.
02 -
Combine the flour, sugar, and butter for the streusel topping. Rub together with your fingers until the butter is incorporated and the mixture has a dry crumbly texture. Set aside.
03 -
In a large mixing bowl, whisk together the vegetable oil, sugar, eggs, milk, and vanilla extract until smooth.
04 -
Add the baking powder, baking soda, and salt to the wet mixture. Whisk well to ensure even incorporation.
05 -
Whisk in the flour until just combined, then gently fold in the chopped rhubarb.
06 -
Divide the batter evenly between the 12 muffin cups. Sprinkle the streusel mixture evenly over the muffins.
07 -
Bake for 23-25 minutes or until a toothpick inserted into the center comes out clean.
08 -
Serve warm with butter, if desired.