Beat the egg whites with the salt until light and frothy. Add the cream of tartar and continue to beat until the whites are stiff enough to hold in peaks.
Beat in the sugar, onetablespoon at a time, until meringue is stiff and glossy. No grains of sugar should be felt when a small amount of the mixture is rubbed between the fingers.
Pile the meringue lightly on cooled pie filling, spreading the meringue until it touches the edges of the pastry to prevent the meringue from shrinking. Bake for five to six minutes, until the top is brown.