Strawberry Freezer Jam

From the garden

• 1½ lb ripe strawberries, hulled · about 1 quart, to yield 2 cups crushed

From the pantry

• 4 cups granulated sugar · the full amount is required for the set; don't reduce it
• 1¾ oz powdered fruit pectin · one standard box

1. Crush the hulled berries one layer at a time with a potato masher. You want a chunky pulp, not a purée. Measure exactly 2 cups of crushed fruit into a large bowl; exact measures are what make pectin jam set.
2. Stir the sugar into the fruit and let it stand 10 minutes, stirring occasionally, until mostly dissolved and glossy.
3. In a small saucepan, whisk the pectin into 3/4 cup water. Bring to a full boil over high heat, stirring constantly, and boil hard exactly 1 minute.
4. Immediately pour the hot pectin into the fruit and stir a full 3 minutes. A few stray sugar grains are fine. Stop before your arm gives out, not before the 3 minutes.
5. Ladle into clean freezer-safe jars or containers, leaving 1/2 inch of headspace for expansion. Lid them and let stand at room temperature up to 24 hours until set, then move to the freezer.