Place the lemon juice and strawberries into a large pot and heat on medium heat.
As the strawberries start to soften, use a potato masher to mash the strawberries to your desired consistency.
Add in the sugar and mix thoroughly until the sugar has dissolved.
Bring to the boil, stirring frequently so the mixture doesn't burn or stick to the bottom of the pot.
If you have any froth appear on the top of the mixture, scoop off with a spoon.
If you have a candy thermometer, it needs to read 105°C (220°F), though you will need to keep a close eye on the mixture when it starts getting around this temperature.
If you don’t have a thermometer, you can use the jam / cold plate test. Before starting your jam, simply place 3 or 4 small plates in the freezer. When you think the jam may be ready, place a small teaspoon amount of jam onto one of the cold plates from the freezer and let it sit for about 30 seconds. Then run your finger through the middle of the blob of jam. If the line starts to fill back over, it means the jam is too runny and is not ready yet, so keep cooking and repeat again in about five minutes. If the line remains, then the jam has reached setting point and is ready.
Fill your sterilised jars with the jam and seal them while they are still warm.
Nutritional information is an estimate and provided as a courtesy. The values may vary according to the ingredients and tools that are used. Please use your preferred nutritional calculator for more detailed information.