The recipes for orange cello and limoncello are nearly identical, so if you've made homemade limoncello (and why wouldn't you?) then you're already on the right track. For this recipe you'll need to strip the peel from 10 oranges, making sure to avoid the bitter piths. Add these to a large jar and fill with vodka. Shake and set aside in a cool, dark place for 2 weeks. Open and add a simple syrup made from 1 1/2 c. sugar and 2 c. water. Let sit for another 2 weeks, shaking daily, before opening for use.