Preheat the Oven: Begin by preheating your oven to 325°F (165°C). This step is crucial as it ensures that the bread cooks evenly and thoroughly. While the oven heats up, take the time to lightly grease two 9x5-inch loaf pans to prevent sticking.
Combine Milk and Lemon Juice: In a small bowl, stir together the milk, lemon juice, and vanilla extract. Let this mixture sit for about 10 minutes.
Mix Dry Ingredients: In a large mixing bowl, combine brown sugar, vegetable oil, and the egg. Beat them together until smooth and well-blended.
Combine Ingredients: Gradually add the flour, salt, and baking soda to the sugar mixture, alternating with the milk mixture, just until combined.
Fold in Rhubarb and Walnuts: Gently fold in the chopped rhubarb and walnuts into the batter.
Pour the Batter: Divide the batter evenly between the two prepared loaf pans, smoothing the tops with a spatula.
Prepare the Topping: In a small bowl, combine the remaining brown sugar, melted butter, and ground cinnamon. Sprinkle this mixture generously over the unbaked loaves.
Bake the Bread: Place the loaf pans in the preheated oven and bake for 40-60 minutes.
