JAM IS MADE by cooking fruit and sugar together to the point where the moisture in the fruit evaporates and the sugar and fruit thicken. Most jams in France are made with either equal weights of fruit and sugar, or four parts fruit to three parts sugar (i.e., 1 pound fruit to ¾ pound sugar). I find that these proportions are too sweet for my taste, and therefore use two parts fruit to no more than one part sugar. Using less sugar results in less jam, but a greater intensity of flavor is achieved. The results are expensive but worthwhile, and a little goes a long way.
Although almost any fruit can be used, my three favorites are raspberry, apricot, and strawberry. Both raspberry and apricot work very well with the 2:1 ratio of fruit to sugar, but I find strawberry jam made with this ratio a little sweet. To adjust the sweetness, I either add a little lemon juice, or start by using a ratio of 3:1 to 4:1, which produces a marvelous jam.
Jam cooks in two distinct stages. During the first stage, the moisture of the fruit evaporates, and during the second the fruit and sugar thicken. In the thickening stage, the fruit and sugar can easily stick to the bottom of your pan and burn if they are not stirred frequently.
The recipe and variations that follow are for relatively small quantities of jam. They cook rapidly and are easily prepared. Larger amounts take considerably more time to cook, and should not be tried until you master the process with the smaller quantities. I keep the small quantities of jam in my refrigerator or freezer.