This question already has an answer here:
Found it here. https://twitter.com/JINhktr/status/1141306368495742977
Is とくから a suffix or for 教え? Is it another word entirely? What does it mean?
I think it means something like "This is the way I've been taught to drink sake, so forgive me."?
The 教えとくから part just confuses me since I haven't seen とく used like this before.