Preheat the oven to 350 degrees. Line 2 muffin tins with cupcake liners. Set aside.

In a large bowl mix together the oil and honey until they are well combined.

Add in the brown sugar and mix well.

Beat in the egg and vanilla. Set aside.

In a medium bowl combine the flour, baking soda, baking powder, and salt.

Add half the flour mixture to the oil mixture and mix well.

Stir in the milk to the oil mixture.

Add in the remaining flour mixture and mix until combined.

Fold in the rhubarb and the walnuts.

Fill the prepared muffin cups 2/3 of the way full with the batter. Bake for 25-30 minutes or until the tops are brown and a toothpick inserted into the center comes out clean.