1. Heat the butter in a saucepan, add the flour and cook, stirring with a wooden spoon for 1-2 minutes. Add the milk and sugar; cook stirring 3-4 minutes. Stir in the lime juice and rind, mix well. Allow to cool for a few minutes, then beat inthe egg yolks, one by one. Beat the egg 2 whites with a pinch of salt to stiff peaks. Add 2 tablespoons of the beaten egg whites into the souffle mixture and blend well. Fold in the rest of the whites. Pour into a buttered soufflé mold. Bake in a 375º oven for 30-35 minutes. Serve immediately.