Serve these sweet-sour oranges like a chutney.
Place orange slices in a large stainless-steel saucepan; cover with cold water. Simmer until skins are tender, about 1 1/4 hours.
Remove oranges with a slotted spoon; place in a colander to drain. Discard water.
Combine sugar and vinegar in the same saucepan; stir over low heat. Bring to a boil. Add spices; simmer 10 minutes.
Add oranges and simmer, covered, for 40 minutes, or until skins are translucent. Cool.
Layer oranges in sterilized jars, cover with syrup, and seal. The oranges can be used right away, but the flavor will be improved by waiting 4 to 6 weeks.