Combine the chopped rhubarb and halved strawberries in a large saucepan or Dutch oven.
Pour the sugar over the fruit mixture and stir gently to coat all the pieces evenly.
Place the saucepan over medium heat and bring the mixture to a gentle simmer, watching for bubbling around the edges.
Stir frequently with a wooden spoon to help the fruit break down and prevent sticking, releasing fragrant, sweet-tart aroma.
Reduce heat slightly and continue to cook, stirring occasionally, for about 20-25 minutes until the mixture has thickened and the fruit is very soft.
Use the back of a spoon to mash any remaining large fruit pieces if you prefer a finer texture.
Once the jam is thick and glossy and has reached your desired consistency, remove it from heat and let it cool slightly before transferring to jars.
Pour the warm jam into sterilized jars, leaving a small headspace, and seal them tightly.
Allow the jars to cool completely at room temperature, then store in the refrigerator or process in a water bath for longer shelf stability.
