I encourage my children to shower before we eat, because I enjoy dinner, and nothing ruins the taste of a good meal like an unwashed soccer, tennis or basketball player. If I can smell them from ten feet away, the meal I've prepared loses its appeal. But before they get home, when I'm cooking that meal, I use my sense of smell to decide what the dish needs, without the risk of ruining the dish with a seasoning that just doesn't work. How?
As I cook, I taste as I go, but I also smell, and smell again. If I'm eying a pile of thyme, wondering if it would be just the thing to add to my pot of mushroom and onion soup, I take a sniff before I commit, holding the thyme over the pot, stirring the air with my hand to mingle the scents. If they smell right together, they'll probably taste right. (By the way, the thyme was delicious in the mushroom and onion soup!)
The other day, one of my sons asked me what I was doing, waving my hand over a pot with my eyes closed, inhaling deeply. I showed him my technique, thereby guaranteeing that he will be the biggest weirdo in his first college apartment. But it works!
Using my sense of smell in the kitchen has helped me cook more instinctively, and allowed me to experiment more. The smell test is a pretty good indicator of taste, so I run less risk of ruining a dish with the wrong ingredient.
Do you use your nose in the kitchen?