Rye bread is made with hot water and flour for ease of handling. According to the recipe query, the reason why hot water and flour are used for rye bread is that hot water can promote the denaturation of gluten and starch, making the dough softer and easier to manipulate. Rye flour contains very little gluten, so when baking rye bread, warm water needs to be added to further activate the gluten and make the dough more pliable.