Peel enough oranges that would fill a 750ml bottle. Make sure not to peel too deep to avoid including the white pith.
If you decide to fill the 750ml bottle with orange peel, make sure you have another empty bottle to use to store your orange liqueur later. Speaking from experience, taking the orange peel out of your bottle is next to impossible!
Allow the vodka & peel to soak for 5-10 days, and make sure the peel is not exposed to any air. The air exposure will cause the peel to give an off flavor and it will ruin your entire batch.
After 5-10 days, strain the vodka from the orange peel.
The next step depends entirely on your palate and what you are looking for in an orange liqueur. Combine the 1:1 simple syrup with the strained orange vodka until it is sweetened to your liking.