This chapter of the guide to Dragon Ball Z: Kakarot has a walkthrough for the Mysterious Power Reading side quest.
Time frame: From Attack of the Saiyans - Episode 7: Intermission to Episode 7: Intermission
Reward: 5,292 EXP, D Medal, Romantic Apron, Mega Mass Lvl 1
Where to start: West Area, as Gohan.
Start this mission by talking to Bulma. She is waiting for you near the fountain in Capsule Corp.
You need to move to the Lucca Village.
Your task is to get to the plants located around the crater. You may encounter opponents - defeat them to get inside.
Inspect the plant and return to Bulma. This will complete the quest.