Bring a small saucepan of water to boil. Meanwhile, using a channel (cocktail) zester, zest oranges to make long, curly strips of zest; or, using a vegetable peeler, cut wide strips of zest and then use a knife to slice into 1/4-in. strips. Boil zest 5 minutes. Drain; repeat. Set blanched zest aside.
Put sugar and 1/4 cup water in pan and bring to a simmer over medium heat, stirring until sugar dissolves. Add blanched orange zest, cover, and simmer 3 minutes.
Transfer zest and syrup to a small jar, let cool, then chill overnight.
Drain zest on paper towels before using.
Make ahead: Keeps at least 2 months, chilled.