Before you do anything else in the kitchen, you need to do this. If you don't have a microplane grater already, you need to go out and buy one. They sell them at most kitchen stores these days, so you shouldn't have any problem finding one. There's so many things you can do with one, I don't think any one person will figure them all out. But today, we have a purpose.
Okay, you have your microplane? Next thing you need is an orange. What the heck, grab two of them. Okay, got 'em? Look at the shiny outer layer that we call the peel, or rind. You know, the part that you always peel off and throw away, in favor of the juicy goodness inside? Believe it or not, that rind has a lot of flavor tucked away. That's why chefs call it zest. The flavor is packed into some pretty concentrated oils, and we're not going to waste them anymore.
Get a small saucepan and put about half to a full cup of olive oil in it, depending on how strong you want it to be. Don't bother using extra virgin olive oil for this one, it has a lot of subtle flavors that are heat sensitive, and most of them are not going to be able to handle even the low heat that we'll be using. Take your microplane and remove all of the zest that you can get to from those oranges. Leave the white stuff behind, it's called pith, and it's pretty bitter. You only want the orange bit. Go ahead and add the zest to the oil, and give it some heat. You don't need much. In fact, if it's sizzling, it's too hot. The last thing we want to do is fry anything.
Now, let the oil sit on low heat for about half an hour. It won't hurt anything if it goes a little longer. Then turn off the heat and let it cool. Then move to a non-reactive container (plastic, glass, stainless steel, but not aluminum) and let chill in the fridge overnight. In the morning you can strain it, or just leave it as it is. Guess what! You have orange oil!
What can you do with orange oil? Well, technically you could cook with it, but the flavors are probably a little too subtle, and would get lost. So I recommend a cold application. Mix 2 1/2 parts orange oil with 1 part red wine vinegar. If you decided to leave the zest in, bonus! This, by itself, makes a killer salad dressing. It might also go well on a sandwich. Or you could use it as a vegetable marinade. Just remember, you probably don't want to keep it around for more than a week, so stick with smaller quantities when you make it.
Now, here's the key: you don't have to use olive oil. You may prefer to use a more neutral oil, such as canola oil. Heck, you don't have to use oil at all! You can do exactly the same thing with vinegar. Try making an orange champaigne vinegar sometime. Oh, and did I mention you don't have to use orange either? Any citrus zest will work. But that's not all! Any herb or spice, dried or fresh, will work. But there are some things to remember. The flavors in dried herbs and spices tend to be more fat soluble, while the flavors in fresh tend to be more water soluble. So dried tends to be better for oils, and fresh tends to be better for vinegars. Zest is a little different. Even though it's technically fresh, all of the flavor is already in oils. So it tends to infuse better into oils.
Now, I want everyone to try this out, just once. I'm going to be posting a recipe in a few days that makes use of infused oils.