This page of the Elex 2 game guide contains a walkthrough of the Spoil the Soup quest. You will receive it from Wardek after completing The Lost Father quest.
Conversation with Wardek
All you need to do during this mission is to talk to Wardek, but first you need to complete the Voices from the Darkness quest, which involves visiting an abandoned factory near the Depository - you can find its walkthrough on a separate page of this guide. After completing the quest, return to Wardek to complete the Spoilt the Soup quest and receive the Antibiotics quest.