He's the person in charge of material prep.
Please pour two parts water for one part of the ingredient.
My favorite food is udon noodles and the ingredients are just wheat flour, salt, and water.
You have to pay a fee for the material you use to make food. Those are the ingredients you're paying for! Imagine making a list of all of the materials you need to make a stew, then making sure you have enough to pay the fees, so you'll have all the ingredients you need to make it.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.