I am currently putting together a book called Salute, Jonathan!, a textbook for the language Occidental/Interlingue that follows the nature method used in such books as Lingua latina per se illustrata. The book is written entirely in Occidental, but after it is completed I will add some separate English commentary in the way the Nature Method Institute did it: the textbook is in the target language only, with separate chapters for the use of a teacher using it in the classroom.
The English section after the Occidental text is completed will be similar to the Haas grammar but with each part illustrated using examples from the story that the reader is supposed to have completed by then (thus there will be a larger spoiler tag on the top):
As of July 20 2019 I have the whole story written in Occidental (100,000+ words) and am adding it here chapter by chapter. Once that comes into form the English supplementary chapters will follow.
Update 10 October 2021: I am currently recording the audio for the book and have finished up to chapter 88. Recording and editing the audio up to chapter 100 will probably be done near the end of the month.