A lot of the texts for beginners like you describe that are published by the big publishers are geared to immigrants to English speaking countries, so the context is quite different.
There is an online resource that is technically geared to children, but which has a lot of high quality resources that could be used with adults. (I work with adults, so am also sensitive to using "childish" materials with them).
Check out www.readinga-z.com . It has a number of sister sites, and it and www.reading-tutors.com have excellent materials for introducing the alphabet. They are all downloadable, without a lot of clutter on the page. You need a subscription to access the materials, but if you contact the organization they can give you a trial.
I hope this helps.