Preheat oven to 325 degrees F. Mix the well-beaten egg with the sugar and salt. Add one-half of scalded half and half in a very fine stream, stirring vigorously all the while. Mix the sour cream into the remaining half and half, and stir into the first mixture, along with the lemon juice. Add the rice, currants (or raisins), and nutmeg. Mix together well. Pour the mixture into a buttered casserole, and set it in a shallow pan. Pour hot water into the pan, so that it comes about half-way up the side of the casserole. Grate the fresh nutmeg on top of the custard. Bake 1 1/2 hours, or until the custard is set and turning golden on top. Just for you, Dee...enjoy!