When I lived in the Mediterranean, I used to try to improve my French by reading women's magazines, and I was often intrigued by the recipes there. One technique that I have tried and loved is preserving citrus fruit in olive oil. The oils in the skin of the fruit will leach into the olive oil, both preserving the fruits and flavouring the oil, and leaving you with a delicious-tasting result!
Enough of the preliminaries--let's get on to the techniques. This is simple and easy to do, and will make a great gift for just about anyone, too!
Wash your fruit thoroughly before beginning. Slice oranges, lemons, limes or grapefruits into small pieces (I like to use very thin crosswise cuts for everything except grapefruits). If the fruit is exceptionally bitter, you may salt it and drain for an hour, but I prefer, where possible, to leave it alone. Pack fruit tightly into wiretopped jar and fill with a high-quality olive oil. Move the jar about carefully, so that any trapped air bubbles escape to the surface (you can pound it on a towel folded on the table. Make sure that the oil is at least a half-inch above the fruit and that no air bubbles remain (the air will make it spoil).
Now for the hardest part of the recipe--you have to put the jar in a dark place, and leave it alone for at least a month--six weeks or longer is preferred for the best result. When you are finished, you can take it out, use the olive oil, and eat the fruit as you go (make sure the oil level continues to stay a half-inch above the fruit in the jar). Delicioso!