Here’s a recipe I got several years ago when I took a one-evening class at a local college’s culinary program. The theme was cordials & liqueurs. Did it with a friend, and it was really fun. We got to make everything and take samples home (except this recipe, which would not have been portable). We learned to make Irish Cream, a Creme de Cassis (black currant) liqueur, Dutch chocolate mint liqueur, Brandied Sweet Dark Cherries, Brandied Cranberry-Cherry Relish, Orange Hot & Sweet Mustard, and Spicy Holiday Nuts. I can post those recipes if anyone wants them.
This makes the most gorgeous, fresh-tasting liqueur EVER! I’ve made it several times, with great results each time, although after the first run-through, I reduced the amount of simple syrup I added. Also, the lemon-lime combination was fantastic, and it was a beautiful light green color, too. Add it to Coca-Cola for a pseudo Cuba Libre. For that matter, you could use light rum or gin and see how that works out.
Homemade Orange Liqueur
Ingredients:
1 quart unflavored Vodka (not the cheapest crap, but don’t use up your good Grey Goose)
3 fresh oranges or tangerines
3 cups water
3 cups granulated sugar
Equipment:
Gallon Jar with tight fitting lid
Cheesecloth & butcher’s string
Saucepan & large spoon
Dry measure cup
Funnel
Gift Bottle(s) & labels
Instructions
• Sanitize the gallon jar.
• Pour Vodka into jar.
• Wash fruit, and remove any stickers. ** Do not cut it up or score the skin. ** Place the whole oranges/tangerines into the center of a piece of cheesecloth. Draw up the corners, tie opposite sides to form a bundle. Tie the bundle together with string, allowing 5-6” of the string on each side of the knot.
• Holding the bundle by the string, shove it through the mouth of the jar and hang it so it is dangling over** BUT NOT TOUCHING** the alcohol. This is very important. Don’t allow the fruit to touch the alcohol, or the oil from the skin of the fruit will adulterate the vodka. You may want to practice this maneuver before pouring the vodka into the jar. 
• Leave the string outside the jar and screw the lid on, keeping the fruit bundle suspended above the alcohol. Tie a big knot in the string to keep it from slipping further into the jar.
• Label the jar with the date. Store in a cool, dark place for one to three months to age.
• Mark you calendar! This is like magic, really! The alcohol fumes circulate around the fruit, and some how it infuses the alcohol with gorgeous fresh flavor. For best results, age at least two months, but not much longer than three.
After Aging Instructions
• Prepare simple syrup: Bring water to a boil in saucepan over medium heat, then add sugar and simmer about 5 minutes, or until sugar is completely dissolved.
• Remove pan from heat, and allow syrup to cool completely, about 2 hours.
• Holding the strings of the bundle, carefully open Vodka jar. Remove the fruit bundle and reserve the fruit for making marinades or other uses.
• Pour the cooled simple syrup into the Vodka. Let mixture stand for at least 3 days.
• Pour the finished liqueur into gift bottles with your special label.
Try other citrus fruits, like lemons and limes, or peaches, or just about anything. Remember to use whole fruit. I probably wouldn’t recommend using more than two types of fruit, but hey, it’s your booze, so do whatever you want with it. You may find that the original recipe makes a sweeter (or less sweet) liqueur than you prefer, so you can adjust the proportions if you like. Just remember to use a 1:1 ratio for the simple syrup (i.e. 2.5 cups water & 2.5 cups sugar, or 2 cups water & 2 cups sugar).