Setting up a restaurant for myself

Current issue: It not clear how to setup a simple auto-deduction of components used in the bill of materials of a product, when the product is sold in POS.

Example: 
Product 1: egg <-- 20 available in warehouse 1
Product 2: bun <-- 10 available in warehouse 1
Product 3: Egg sandwich  <-- Bill of Material: 2 eggs and 1 bun

When i sell one unit of Egg sandwich, i expect 2 eggs and 1 bun to be automatically deducted from inventory

I have looked at routes, MTO option etc.. but not very clear. Pls share if there is text or video that explains this clearly.