Slightly modified from epicurious.com
4 large oranges, 1/4″ of top and bottom cut off
3 3/4 cups sugar, divided
3 cups water
Set a large pot of water on to boil.
For each orange, make a vertical cut, just through the peel and pith, at each compass point. Remove each quarter of orange skin, including the pith, in one piece. (Eat the peeled orange sections!) Cut each piece into 1/4″-wide strips. Put all the strips into the large pot of boiling water and cook for 15 minutes. Drain, rinse, and drain again.
In a medium-sized pot over medium heat, bring 3 cups sugar and 3 cups water to boil, stirring to dissolve sugar. Add peel and return to boil. Reduce heat and simmer until peel is very soft, about 45 minutes. (I will try 35 or 40 minutes next time for a little more chew.) Drain, saving the delicious orange simple syrup for other use: soaking a cake, sweetening tea, cocktails, etc..
On a large rimmed baking sheet, pour the remaining 3/4 cup sugar, spreading it out into an even layer in the center of the sheet. Put the cooked peels onto the sugar, and toss them to coat thoroughly. Lift them out of the sugar and place them on a parchment- or foil-lined tray. Let stand until coating is dry, 1-3 days.
Make ahead: wrap and freeze for up to 2 months.