Wash the oranges, then slice one orange into rounds. Zest the second orange, then squeeze out its juice.
Place all ingredients in a large pot and cook it over medium heat until it just barely reaches a simmer. Immediately reduce the heat to low, cover with a lid, and let it simmer for 30-45 minutes. → Avoid letting it bubble — you don't want to boil off the alcohol.
Pour the mulled wine through a fine-mesh sieve and serve warm in your favorite mug! Feel free to sweeten with more maple syrup or add a shot of rum, brandy, or amaretto.
Notes
Make Ahead & Storage: Pour the finished mulled wine into a glass bottle and store it in the refrigerator for up to 5 days. Can easily be prepared in advance!Reheat in a small pot (only to a light simmering) and enjoy warm!Red Wine: I recommended to use semi-dry red wine such as a Merlot, Pinot Noir, or Tempranillo. I usually go for a semi-sweet Tempranillo.