1. Preheat the oven to 375°. Generously grease a 9x5-inch loaf pan. In a small bowl, combine the milk and lemon juice. Set aside for 10 to 15 minutes or until the milk has soured or become slightly thickened.

2. Combine the flour, brown sugar, baking powder, soda, and salt in a large mixing bowl. Whisk to blend thoroughly. In a separate bowl, whisk together the soured milk, egg, oil, and vanilla. Add to the dry ingredients and blend well. Stir in the rhubarb and pecans. Pour into the prepared loaf pan.

3. Whisk together the granulated sugar and cinnamon. Sprinkle over the unbaked loaf. Place in the oven and bake for 50 minutes to 1 hour or until a wooden pick inserted in the center comes out clean.