To sterilize jars, submerge in boiling water for ten minutes. Jars should remain in hot water until they are ready to be filled. Try this jam with yogurt or toast topped with fresh ricotta cheese.
- 3 pounds yellow peaches, peeled
- 1/3 cup fresh lemon juice
- 4 3/4 cups sugar
- 4 large sprigs fresh rosemary
Halve and pit peaches, then cut into 1/2-inch-thick wedges. Transfer to a large bowl. Add lemon juice; toss. Add sugar and rosemary; toss. Cover; let stand, tossing every hour, for 4 hours (sugar should be completely dissolved).
Put peach mixture into a large, wide pot. Bring to a boil over medium-high heat. Cook until liquid is syrupy, 12 to 13 minutes. Crush lightly with a potato masher, leaving one-quarter of the wedges intact. Skim foam from surface. Discard rosemary sprigs.
Seal and process: Fill hot, sterilized 4-ounce jars with hot jam, leaving 1/4 inch space in each jar's neck. Wipe rims with a clean, damp cloth; cover tightly with sterilized lids and screw rings. Transfer jars, using tongs or a jar clamp, to the rack of a large canning pot filled with hot water, keeping jars upright; cover with water by 2 inches. (Jars should be spaced 1 inch apart and should not touch sides of pot.) Cover; bring to a boil. Process jars in gently boiling water 5 minutes. Transfer to a rack; let cool 24 hours. If lids pop back when pressed, they are not sealed; refrigerate immediately, and use within 1 month. Sealed jars can be stored in a cool, dark place up to 1 year.