Can you recount the story of the Yoga practitioner who visited Sai Baba in Chapter 23?

Certainly. Chapter 23 tells of a practitioner of Yoga (Yogabhyasi) who came for Baba's darshan with Nanasaheb Chandorkar. This man was highly learned, having thoroughly studied the Yoga Shastras of Patanjali and others, yet he had a significant problem: he could not achieve the state of Samadhi (intense meditation) for even a moment. He held the intent in his heart that since Sai Maharaj was a "King of Yogis," His grace would remove his doubts and allow him to achieve Samadhi. However, upon arriving at the Masjid for this profound spiritual purpose, the first thing he saw was Sai Baba eating bread with onions.