This is a classic Canadian recipe. Simple and delicious. It's not thick, like pectin-based jams, but I think it's truer to the fruit and more delicious. Try it with Lemon-Walnut Scones - perfect pairing. ETA: Many people have asked me why this recipe contains butter. The butter prevents the jam from foaming while you're cooking it - the foam is unattractive and spoils the appearance of the jam. Adding a little butter eliminates this problem.
- In a large saucepan, bring strawberries up to a simmer over medium-low heat, mashing roughly with a potato masher or flat spoon.
- Add sugar and lemon juice, stir, and bring up to a simmer for 2 minutes.
- Add butter and bring to a vigorous boil, stirring often, and cook for 10 to 20 minutes, periodically measuring the viscosity of the jam by dabbing a spoonful onto a plate and tipping the plate.
- Once the jam slows its drip down the plate (it should no longer run like a syrup), remove from heat and skim off foam.
- Fill jars that have been washed, rinsed, dried and boiled in a pot of water for 3 minutes to 1/4 inch from the top.
- Fasten lids securely and boil jars in a vat of water (be sure jars are completely submerged) for 15 minutes.
- Remove jars with tongs and let cool upright.
- Check for secure seals on jars (lid should not spring when touched) and store in a cool place away from light for up to a year.
- Any jars that do not achieve a proper seal should be refrigerated.