How exactly did Sai Baba prove to Cholkar that he knew about his secret penance involving sugar?

Sai Baba demonstrated his omniscience to Cholkar in a very specific and personal way. As detailed in Chapter 15, after Cholkar had fulfilled his vow and was visiting with Mr. Jog, Baba gave a pointed instruction. He told Jog, 'Give him cups of tea, well-filled with sugar.' This command was highly significant because Baba himself did not drink tea, and more importantly, it directly addressed Cholkar's secret penance of avoiding sugar. Hearing these meaningful words, Cholkar was amazed and overcome with emotion, realizing that Baba was intimately aware of the vow, the long delay, and the private sacrifice he had made.