Wash and dry the Mason jars or freezer-safe containers.

Using a large baking dish, such as a 9x13-inch pan, mash the strawberries with a potato masher. Do not leave any large pieces of strawberries.

In a large bowl, add exactly 3 ¼ cups of mashed strawberries and the lemon juice. Sprinkle the MCP (powdered pectin) evenly over the berries and stir to combine.

Measure the 4 ½ cups of sugar into a separate bowl. Set two timers, one for 30 minutes and another for 5 minutes. Before each stir, add ¾ cup of the sugar. Stir the jam every 5 minutes until the 30-minute timer goes off and all of the sugar has been added. Don't rush this step. The gradual addition of the sugar and regular stirring help dissolve the sugar and give the jam its smooth texture.

After the 30 minutes are up, stir continuously for an additional 3 minutes to dissolve any remaining sugar.

Taste the jam with a clean spoon. If it still has a grainy texture, continue stirring for another 3 minutes. If not, the jam is ready.

Using a wide-mouth funnel and a measuring cup, carefully pour the strawberry jam into the containers, leaving ½ inch of headspace for expansion as the jam freezes. Wipe the rims clean and screw on the lids.

Let the jam sit on the countertop for 24 hours.

After 24 hours, store the jam in the refrigerator for up to 3 weeks or freeze for up to 1 year. Defrost before using.

Label the jars with the year using freezer tape or on the lids with permanent marker to help keep your freezer organized.