Place the halved strawberries in a bowl. Add the sugar and mix well. Refrigerate overnight or macerate for a few hours at room temperature.
Transfer strawberries with the juices to a jam pan. Bring to a boil and cook over medium-high heat stirring every few minutes until the jam begins to thicken and starts to stick to the bottom of the pan slightly. Skim off the white foam.
Once the jam starts to stick to the bottom of the pan, lower the heat to low and continue cooking constantly stirring and scraping the bottom of the pan very well. Cook until such time as when you run the spatula quickly from one side to the other across the bottom of the pot, you can observe as long as a 6-7 inch long gap before it starts to fill back up.
Fill the hot jars with the jam using a clean ladle and a canning funnel, leaving a 1/2" headspace.
Wipe the rims of the jars, put on the lids and the bands. Tighten the bands finger-tight.
Process in a water bath canner for 10 minutes (assuming 0 - 1,000 feet above sea level), making sure there is at least an inch of water above the lids.
After processing, remove the jars from the canner and let them cool down. Check the seals, then move to a dry, cool and dark place for storage. This strawberry jam, if properly sealed, will have a long shelf life, up to 3 years before you will notice a loss of taste quality.
One serving in this recipe is a quarter of an 8 oz jar or 2 ounces.