The phrase "soaking mixture" refers to a liquid or solution that is used to soak or immerse something in order to achieve a desired result. Full definition
Now spoon your bath tea and salt soak mixture into your decorated muslin bags. (soapdelinews.com)
Drain the soaking mixture, reserving 1/4 cup of the liquid, and add the chilies and dried tomatoes to a food processor with the tomatoes, jalapeno powder, garlic and salt. (yummysmells.ca)
Stir the soaking mixture between each slice of bread. (plateofplants.com)