Preheat the oven to 350°F. Prepare three 6 × 3 × 2-inch miniature loaf pans by greasing them and lining the bottoms with parchment paper (see Note).
In a medium heatproof mixing bowl, pour the boiling water over the raisins and baking soda. Set aside to cool.
In a medium mixing bowl, sift together the flour, sugar, and salt. Stir in the bran flake crumbs. Lightly beat together the egg and oil, and stir into the flour mixture. Stir in the cooled raisins and water. Divide the batter evenly among the three pans. Bake for about 30 minutes, or until a toothpick inserted in the center comes out clean. Cool in the pans for about 10 minutes, then turn out onto racks for cooling.
To bake in cans, heavily grease and flour the insides of three 16-ounce cans.