Place 2 small plates in freezer to chill.

Using a potato masher, crush strawberries in a 6 to 8-quart heavy saucepan until fruit is mostly broken down, but leave a few chunks.

Stir in sugar, apple, and lemon juice.

Stir over low heat until the sugar is dissolved. Increase heat to medium-high, and bring the mixture to a full rolling boil. Boil, stirring often until the mixture reaches 217- 220 degrees It will be very frothy and requires almost constant stirring to prevent it from boiling over and burning.

Remove pot from heat.

Test consistency by placing a teaspoon of jam on the chilled plate and freeze for 2 minutes. Drag your finger through jam on plate; jam has correct consistency when your finger leaves a distinct trail. If the jam is runny, return the pot to heat and simmer for 1 to 3 minutes longer before retesting.

Skim foam from surface of jam using a spoon.

Ladle hot jam into hot jars leaving 1/4 inch headspace. Wipe rim. Center lid on jar. Apply band until fit is fingertip tight.

Slide wooden skewer along the inside edge of the jar and drag upward to remove air bubbles.

Place jars in a large pot and make sure tops are covered with at least an inch of water. Process filled jars in boiling water for 10 minutes, adjusting for altitude.

Remove jars and cool.

Check lids for seal after 24 hours. The lid should not flex up and down when the center is pressed.

Refrigerate jam once the seal is broken.