To each kilo of fruit, add 1 kilo of sugar. Weigh the fruit after you cut off the green stalks. If they are large fruit, cut in half, otherwise leave whole. You can leave in the pot overnight and cook the next day. The sugar will melt in the strawberry juice. You will also need to add the juice of 1/2 a lemon or lime.
Start cooking slowly, and stirring constantly until the sugar is all melted, and it starts to boil. Let it boil fairly rapidly for about 20 minutes. Stir from time to time - don't let it stick. After 15 minutes, test to see if the jam is setting. Put a teaspoon on a saucer in the fridge, and if it crinkles when you run your finger though it then it is done. Turn off the stove.
Throw in a dob of butter, and stir it through. You will notice that there is a scum all over the top of the jam. Yuk! you can eat it, no problems, it just does not look so good. Scoop it off with a spoon.
If you come to my house we can scones, and jam and cream!