- Combine the strawberries, rhubarb, sugar, and lemon juice in a large saucepan. Stir well to evenly distribute the sugar and ingredients. 
- Place the saucepan over medium heat and bring the mixture to a gentle simmer, stirring frequently. Watch for bubbling appearance and a sweet aroma from the fruit as it starts to soften. 
- Reduce the heat to low and add the cinnamon. Continue to simmer, stirring occasionally, until the mixture thickens slightly and the fruit is fully softened, about 15-20 minutes. The jam should appear glossy and coat the back of a spoon. 
- Remove the saucepan from heat and pour the hot jam into sterilized jars or bowls. Let it cool slightly before using or storing. 
- Once cooled, the jam has a vibrant, chunky appearance with visible fruit pieces suspended in thickened syrup. Serve it spread on bread or as a topping for desserts.