Can you tell me the story from Chapter 23 about the Yogi who came to Sai Baba seeking help with Samadhi?

Certainly. Chapter 23 narrates an incident involving a practitioner of Yoga (Yogabhyasi) who visited the Masjid with Nanasaheb Chandorkar. This Yogi was an expert in the Yoga Shastras of Patanjali but was deeply frustrated because he could not achieve Samadhi (intense meditation) for even a moment. He came to Shirdi with the specific hope that Sai Baba, whom he considered a "King of Yogis," would show him grace and remove his doubts, allowing him to finally attain Samadhi. However, upon arriving for darshan, his spiritual expectations were met with a mundane sight: he saw Sai Baba simply eating bread (bhakar) with onions, illustrating that a saint's true state is beyond such external actions.