- 1 cup milk
- 1 tablespoon lemon juice
- 1 teaspoon vanilla extract
- 1 ¾ cups brown sugar, divided
- ⅔ cup vegetable oil
- 1 large egg
- 2 ½ cups all-purpose flour
- 1 teaspoon salt
- 1 teaspoon baking soda
- 1 ½ cups chopped rhubarb
- ½ cup chopped walnuts
- ½ teaspoon ground cinnamon
- 1 tablespoon butter, melted
Preheat the oven to 325 degrees F (165 degrees C). Lightly grease two 9×5-inch loaf pans.
Stir together milk, lemon juice, and vanilla in a small bowl; let stand for 10 minutes.
Mix together 1 1/2 cups brown sugar, oil, and egg in a large bowl. Combine flour, salt, and baking soda, and stir into sugar mixture alternately with milk mixture just until combined. Fold in rhubarb and walnuts. Pour batter into prepared loaf pans.
Combine remaining 1/4 cup brown sugar, butter, and cinnamon in a small bowl. Sprinkle this mixture over the unbaked loaves.
Bake in the preheated oven until a toothpick inserted into the center of a loaf comes out clean, about 40 minutes.