I have several recipes for waffles but I always come back to this one. I only use NATRON in my waffles but I have substituted NATRON with baking soda in this recipe. I think both NATRON and SOURED MILK is hard to find in the US. Norwegians always use a 5-heart iron to make waffles but it's no requirement. Serve them warm with any topping your heart desires.