Pour the wine into a saucepan and place it over low heat.
Add the cinnamon sticks, whole cloves, and orange zest to the wine.
Slice the orange in half and squeeze in the juice, then add the juice to the saucepan.
Gently stir the mixture with a wooden spoon, releasing fragrant aromas and blending the flavors.
Increase the heat slightly to bring the mixture to a gentle simmer—small bubbles should form around the edges, but avoid boiling.
Let the wine simmer on low heat for about 20-30 minutes, allowing spices and citrus to infuse fully and aromas to develop.
Remove the saucepan from heat, then stir in honey or sugar, tasting and adjusting sweetness as desired.
Strain the mulled wine through a fine sieve to remove spices and citrus zest, resulting in a smooth, aromatic liquid.
Pour the warm, spiced wine into mugs or glasses, garnishing with additional orange slices or cinnamon sticks if desired.