"This is a recipe from my great-grandma with simple ingredients. This bread is moist, healthy, and delicious. You can easily cut back on the sugar and switch out ingredients depending on taste or dietary restrictions. I love to use dried cranberries instead of raisins, reducing the sugar by several tablespoons when I do."
Preheat oven to 350 degrees F (175 degrees C). Grease and flour a 9x13-inch loaf pan.
Bring raisins and water to a boil in a small saucepan, reduce heat to medium, and boil 5 minutes; set aside to cool.
Mix rolled oats, bran cereal, whole wheat flour, sugar, and salt in a bowl. Mix milk with lemon juice in a small bowl and let stand 1 or 2 minutes to sour. Stir baking soda into sour milk until dissolved. Pour milk mixture into dry ingredients; beat egg into the mixture. Stir raisins and their liquid into the batter. Pour batter into prepared pan.
Bake in the preheated oven until a toothpick inserted into the middle comes out clean, about 1 hour. Cool in pan for 15 minutes before removing to finish cooling on a wire rack.