How did Sai Baba demonstrate his omniscience regarding Cholkar's secret vow of abstaining from sugar?

After Cholkar finally made it to Shirdi, had his darshan, and fulfilled his original vow by distributing sugar, he was a guest of a man named Jog. According to chapter 15, as Cholkar and Jog were about to leave, Sai Baba specifically instructed Jog to "Give him cups of tea, well-filled with sugar." This instruction was deeply meaningful because Baba did not typically drink tea, and the specific mention of filling the cups with sugar was a direct and miraculous confirmation to Cholkar that Baba was aware of his secret, personal penance of avoiding sugar during the period of delay. This revelation brought tears of joy to Cholkar's eyes.