Preparation

• In a large nonreactive bowl, gently toss together the strawberries, cherries, and sugar. Cover and let stand at room temperature for 1–2 hours.
• Have ready 6 sterilized jars and their lids. Place 2 or 3 small plates in the freezer.
• Transfer the fruit mixture to a large nonreactive saucepan and add the lemon juice. Bring to a boil over medium-high heat, reduce the heat to medium, and cook, uncovered, stirring frequently, for 10 minutes. Remove from the heat. Drop 1 teaspoon of the jam on a chilled plate; if it sets as it cools, the jam is ready. If not, return the pan to the heat and boil the jam for a few minutes longer, then test again.
• Ladle the hot jam into the jars, leaving 1/4 inch of headspace. Slide a metal chopstick or other thin tool down the side of each jar, between the glass and the jam, four or five times. This will release any air bubbles. Adjust the headspace, if necessary. Wipe the rim of each jar clean and seal tightly with a lid.
• Store the jars in the refrigerator for up to 1 month.