Rub two bananas through a fine sieve. Put half a cup of granulated sugar
in a saucepan with one cup of boiling water, add the banana pulp to it,
let it come to a boil, and skim if necessary. Rub a heaping
tablespoonful of butter with half a tablespoonful of flour, stir into it
a little of the liquid, and then add to that in the saucepan; add the
juice and grated rind of half a lemon, and it is ready to serve.