Place a small plate in freezer. In a large pot, bring tangerines and 6 cups water to a boil over high. Reduce heat to medium and cook at a rapid simmer until tangerine peels are tender, 20 minutes.
Add sugar, increase heat to medium-high, and stir until sugar dissolves. Return to a boil and cook, stirring often, until mixture is thick and darkens slightly, 40 to 45 minutes. To test for doneness, drop a spoonful on frozen plate and freeze 2 minutes. Marmalade is done if it has a slight film that wrinkles when pushed with a finger. If it spreads out and thins immediately, continue cooking. Transfer marmalade to airtight containers, cover, and let cool completely.
To store, refrigerate marmalade up to 1 month, or freeze, up to 6 months.
I LOVE LOVE this recipe. I made it with Satsumas instead of tangerines since I live in Louisiana and it turned out to be one of the best marmalades I have ever eaten. And my family loved it as well. I gave it away in everyone's Christmas baskets.
A word of caution. I had to cook the marmalade for a little longer than it called for, which meant that I lowered the temperature to medium for the last fifteen minutes so it wouldn't burn. All in all, it cooked for about 1 hour 20 minutes.
I made this recipe today and it was awful!
When I opened the lid to check on the marmalade all the seeds were floating on the top.
I tasted the recipe and it was so bad. Words cannot describe how bad it was.
I just researched orange marmalade recipes and they say to remove the seeds as
you slice the oranges. This tangerine marmalade recipe left out that detail.
I will try it again next week end, without the seeds.