adapted from a recipe in Ball's Blue Book of Canning
5 lb bag tangerines
Thinly slice the tangerines (whole), removing any seeds. Use a grater and remove the yellow part of the lemon peel, then cut off the white rind and chop the remaining pulp. Put the sliced tangerines, lemon peel, lemon pulp, and 3-4 large sprigs fresh rosemary into a large pot. Add enough water to almost cover the fruit. Bring to a boil; simmer 5 minutes, then cover and remove from heat. Let set in a cool place 12-18 hours. Cook over medium heat until peel is tender. Remove rosemary sprigs. Add an equal amount of sugar (1 cup sugar per 1 cup cooked fruit mixture). Bring to a gentle boil, stirring often. Cook until the mixture "gels" - I test this by putting some in a bowl and letting it cool, then checking the taste and consistency of the marmalade. When it's to your liking, ladle marmalade into hot jars, cap, and process.