Did Cholkar give up sugar because Sai Baba told him to? Why was Baba so focused on Cholkar's tea?

No, Cholkar's decision to give up sugar was a personal act of penance and was not instructed by Sai Baba. Chapter 15 explains that after Cholkar passed his exam, he faced a delay in fulfilling his vow to distribute sugar candy in Shirdi due to financial hardship. It was during this delay that he, on his own accord, decided to abstain from sugar until the vow was completed. Baba's focus on the tea was not a literal concern for the beverage, as the text clarifies that Baba himself did not drink tea. His instruction to Jog to give Cholkar tea 'well-filled with sugar' was a deliberate and meaningful sign. It was his way of communicating to Cholkar that his secret vow and his personal sacrifice of renouncing sugar were known and accepted, thereby confirming Cholkar's faith in Baba's omniscience.