Once you create your ingredient items and group it into one, you can now group them to the main course. Go to Items--> Add Ingredient Groups to Item. 

In Item Ingredient Group Mapping, select Add Mapping to add your ingredient groups to group with main course.

In Create page, Select your item from drop down in Item Name. Under Drag to add group, the ingredients group will be already available. Drag your ingredient that goes with your main course to the other column and choose Active or Inactive from Mapping Status and Save.

Your grouped ingredients will be displayed when the customer makes an order.