Mixing water with fire does not result in a single tangible substance. Fire is not a substance that can be mixed with water, but rather a chemical reaction involving the rapid oxidation of a combustible material.
When you add water to fire, it generally has a cooling effect and can be used to extinguish the flames by reducing the temperature below the ignition point of the fuel or by blocking the oxygen supply. Water can also be used to create steam when it comes into contact with fire, but this is not considered a mixture.
In summary, mixing water with fire doesn't yield a specific product, but water can be used to control or extinguish fires.