My former employer is making money off my accounts. How can I get him to pay up?

[ELDreamer81]

I left my job in sales because I could no longer deal with my boss. Even though, I left on good terms he told me that whatever I sold I get a commission. He sold two of my accounts and if it weren't for me he would not have known about these accounts. How should I tell him to pay me for those accounts?