"Dutch" sauce traditional (on a steam bath)

In a saucepan, pour cold water, beat off the yolks, carefully separating them from the whites, add salt, beat everything with a whisk and put everything in a water bath. Heat in the bath, gradually adding a piece of butter and continuously whisk, not allowing not only boiling, but even strong heating. Only after each portion of the oil is completely dissolved can the next portion be added to the sauce. If the sauce begins to turn white at the bottom, you should immediately remove the pan from the water bath and continue to beat on the weight until the mass cools slightly. Then you can continue heating in the water bath again. As soon as the sauce thickens, add the lemon juice.