1quartstrawberries, quartered(should be about 4 cups packed)
½tspunsalted butter (optional, reduces foaming)
Start with the berries: rinse them well, hull them, and cut them into quarters, and put them in a large heavy-bottomed pot. (I used my favorite 4 qt pot, which was perfect for the task.) Add the sugar and lemon juice, then stir well, cover with a clean tea towel, and let stand 1 to 2 hours to bring the juice out of the berries. (You can actually let them stand, covered, in the refrigerator overnight, if you need to.)
Meanwhile, prepare jars and any other equipment. Make sure your jars are sparkling clean. Wash the lids in warm water and set aside. Keep the bands handy. Have an extra small jar, or custard cup, clean and ready for any excess jam. Put a couple of small saucers in the freezer to chill so they’ll be ready for testing the jam.
After the fruit macerates with the sugar and lemon juice for hours, there will be plenty of juice in the pan. Cook the jam: add a tiny pat of butter (it reduces foaming), and bring the fruit mixture to a boil, stirring occasionally. Reduce heat somewhat and simmer it until the chunks of fruit are translucent and thoroughly cooked. Blitz the preserves with an immersion blender – this will create a smooth thick texture, and will help the jam cook faster.
Return the preserves to the heat, and continue cooking, stirring often, until it bubbles and looks quite thick. I like to test for doneness by putting a spoonful on a saucer, and chilling it in the refrigerator for 2 minutes. After that time, if I can drag my finger through the jam, and leave a clear track that doesn’t fill in again, it’s ready. In my kitchen, this took about 10 minutes more.
When the jam is ready, remove the pot from the heat. Ladle jam into prepared jars, wipe rims, and apply lids and bands. Anything that won’t fit in your four jars can go into the clean custard cup and chill it in the fridge.
Process for 10 minutes in a boiling water bath or steam canner. Cool jars, label, and store in a dark cool place.