What does Les give as proof that God has honored his teaching ministry?
The proof is changed lives: many people saved out of especially abject sinful backgrounds, coming out of darkness into the light of the Gospel. Those conversions demonstrate that the Lord has honored the teaching ministry, just as Paul pointed to those he led out of idolatry as evidence of his apostleship.
Les teaches that his proof of the pudding is umpteen people who have been saved out of especially abject sinful backgrounds. He says that is his proof that the Lord has honored what they are doing, by seeing so many people come out of darkness and into the light of the Gospel. He parallels this to Paul, who said, "Are not ye my work in the Lord?" The believers were saved out of abject idolatry only because of his ministry. Paul said, "you're the proof of the pudding," and if he were not an apostle, they would still be in paganism. Paul also said his apostleship was proven by them, because he had led them out of dark idolatry.