Peel the mango and cut it into Â½-inch dice. The easiest way to do this is to cut the flesh in a grid pattern while it is attached to the large pit, and then scrape the diced pieces from the pit into a bowl. Measure the mango and place it in a large saucepan along with sugar about half the measure of the fruit (I had 4 C. mango and used 2 C. sugar). Add the ginger. Juice the lime and add the juice to the mango. Cut the shell of the lime into quarters and set aside. If there are seeds, place them in a small cheesecloth bag and set aside. You will later add them to the mango mixture to help develop pectin.
Bring the mango and sugar mixture to a simmer over medium heat, stirring to dissolve the sugar. Pour it into a bowl and add the lime peel and seeds, if any. When the mixture is cool, crumple a piece of parchment paper, set it on top and refrigerate the mixture overnight. (If you have aromatic items in the refrigerator, cover the bowl loosely with plastic wrap. Prepare jars for water bath canning. Place a saucer in the freezer. Remove the lime shells and pour the mango mixture into a large, wide, heavy-bottomed saucepan. Bring it just to a boil over medium-high heat, stirring so that the mixture doesnâ€™t stick to the bottom. Reduce the heat to allow the mixture to simmer just below the boiling point for about 25 minutes or until thick. Stir from time to time to prevent the mixture from scorching. Test for gel by placing a couple of drops on the frozen saucer and pushing it with your finger. If the jam wrinkles, the gel will be fine. You can also tell the jam is done by pulling a spoon across the bottom of the pan. If it leaves a clean line, the mixture is well gelled. Process in a water bath canner for 10 minutes after the water comes to a boil. Turn off the heat, remove the canner lid and let the jars sit for 5 minutes before removing them to a counter to sit undisturbed until sealed.