First, think about your favorite sandwich, and all the steps you’d need to tell someone in order to make their own.
You can organize your comic however you like. Here’s a sample layout:
Panel 1: draw the ingredients
Panel 2: list the ingredients
For the remaining panels, draw the steps of assembling or making your sandwich.
Have fun with it! You can illustrate noises, you can add a character, or you can bring inanimate objects to life by putting faces on food.