Created by JostLori on September 18, 2017
Step 1: Place 2 small plates in freezer to chill. In large saucepan, crush strawberries with potato masher until fruit is mostly broken down. Stir in rhubarb, sugar, apple, lemon zest, and lemon juice and bring to a boil, stirring often, over medium-high heat. When boiling, crush rhubarb gently with potato masher to help it break down, leaving some pieces intact. Once sugar is completely dissolved, boil mixture, stirring and adjusting heat as needed, until thickened and registers 217 to 220 degrees, about 10 to 15 minutes. (Temperature will be lower at higher elevations) Remove pot from heat.
Step 2: To test consistency, place 1 teaspoon of the jam on a chilled plate and freeze for 2 minutes. Drag your finger through jam on plate; jam has correct consistency when your finger leaves distinct trail. If jam is runny, return pot to heat, simmer for 1 to 3 minutes longer before retesting. Remove lemon zest and skim any foam from surface of jam using spoon.
Step 3: Meanwhile, place two 1-cup jars in bowl and place under hot running water until heated through, 1 to 2 minutes; shake dry. Using afunnel and a ladle, portion hot jam into hot jars. Let cool to room temperature, cover, and refrigerate until jam is set, 12 to 24 hours. Jam can be refrigerated for up to 2 months.