Can you tell me the story from Chapter 23 about the yoga practitioner who came to see Baba hoping to achieve Samadhi?

Certainly. Chapter 23 recounts an incident involving a practitioner of Yoga (Yogabhyasi) who had deeply studied the Yoga Shastras of Patanjali but was unable to achieve Samadhi, or intense meditation. Believing Sai Baba to be a "King of Yogis," he came to the Masjid with Nanasaheb Chandorkar, hoping that Baba's grace would remove his doubts and allow him to attain this profound meditative state. However, upon taking Baba's darshan, the yogi was met with a surprising sight: he saw Sai Baba casually eating bread (bhakar) with onions, an ordinary act that challenged his preconceived notions of a great yogic master.