Rinse 2 pounds of fresh strawberries under cool water for 1–2 minutes until clean. Pat dry with paper towels.

Hull each strawberry by removing the green top and white core using a small paring knife or hulling tool. Takes about 10 minutes total.

Place hulled strawberries in a large bowl and crush them with a potato masher or fork until they release their juices and become chunky. Should take 3–5 minutes. Checkpoint: You should see juice pooling and berries breaking apart, but still have visible chunks—not a smooth puree.

Add 2 tablespoons fresh lemon juice and 1 tablespoon lemon zest (use a microplane to zest the lemon) to the crushed strawberries. Stir gently for 30 seconds. Checkpoint: The mixture should look bright red with visible zest specks throughout.

In a small separate bowl, whisk together 1 package powdered pectin (1.75 ounces) and 1/4 cup of the granulated sugar for 30 seconds until no lumps remain. This prevents the pectin from clumping. Checkpoint: The mixture should look like smooth sand with no visible pectin clumps.

Slowly pour the pectin-sugar mixture into the strawberry bowl while stirring constantly with a wooden spoon. Stir vigorously for exactly 2 minutes. You'll feel the mixture start to thicken. Checkpoint: The mixture should be noticeably thicker and the pectin should be fully incorporated with no gritty texture.

Add the remaining 2.75 cups sugar to the strawberry mixture gradually (in 3–4 additions) while stirring constantly. After each addition, stir for 30–45 seconds before adding more. Total stirring time for this step should be about 3 minutes. Checkpoint: The sugar should dissolve completely and the mixture should coat the back of a spoon, thickening more with each addition.

Add 1/4 teaspoon butter to the mixture and stir for 30 seconds until the butter melts and incorporates. A pinch of salt should also be stirred in. Checkpoint: The mixture should be uniform, glossy, and no foam should be visible on the surface.

Skim off any foam from the top of the jam using a spoon and discard. This takes 1–2 minutes and improves the appearance. Checkpoint: The surface should be relatively smooth and foam-free.

Let the jam rest at room temperature (68–72°F) for exactly 24 hours in the bowl. Do not stir or move it during this time. The mixture will continue to thicken as the pectin fully sets. Checkpoint: After 24 hours, the jam should jiggle slightly when you shake the bowl but hold its shape on a spoon. If it's still too thin, stir in 1 teaspoon additional powdered pectin mixed with 2 teaspoons sugar.

Once set, ladle or spoon the jam into clean freezer-safe containers (plastic or glass) or freezer bags, leaving 1/2 inch headspace to allow for expansion. Wipe the rims clean.

Label each container with "Strawberry Freezer Jam" and today's date using a permanent marker.

Freeze at 0°F or below for up to 12 months. To use, thaw a container in the refrigerator overnight (8–12 hours) or at room temperature for 2–3 hours. Once thawed, refrigerate and use within 3 weeks.