Mise in place is simply the act of just reading the directions, fully understanding and preparing yourself for the task you're about to do. If you bought furniture that needed to be assembled, you'd want to practice a variant of mise en place called "reading the directions first" for best results. You should get in the habit of mise en place every time you bake.
if you were going to make fudge that called for condensed soy milk, you would want to make sure you have the sugar and soy milk and the saucepan for the soy milk to be condensed. You would then want to see if you have your chocolate and other ingredients. Running to the store when there's a time-sensitive saucepan of hot caramel on your stove is not an option. My absolute biggest baking blunder has been running to the store for the emergency ingredient I forgot about and having the store end up being closed. For your fudge recipe you would continue mise en place by chopping your chocolate into half-inch pieces and placing them in a metal bowl so you wouldn't have to later scramble to do it on-the-fly.
In the restaurant industry and other fast paced kitchens mise en place goes one step further and becomes a state of mind where evey spare second is used to squeeze productivity out of the kitchen.
Mise en place is also an important habit to get into because it allows you to focus your full attention on your food and your recipe as you bake. Chefs on cooking shows use mise en place so they can devote their resources to the show so it's as simple descript as possible. Watching a chef chop vegetables for 10 minutes is just no good. Mise en place helps keep baking as it should be- low stress and fun.
Mise en place by allanthinks via Flickr
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