Wash and drain the strawberries. Remove the stem and core. Place the clean strawberries in the food processor, one half at a time. Pulse several times until diced but not pureed, unless you like your jam smooth. Pout the strawberries into a tall, heavy bottomed pot. Pulse the remaining strawberries and add to the pot. Pour in the lemon juice and sugar. You can use less sugar but may need to cook longer. Place a small plate in the freezer to test if your jam is cooked to the point of setting.
Heat over high heat, stirring constantly until the sugar dissolves and the mixture comes to boil. Lower the heat to medium-high and continue cooking, stirring frequently. Use a long-handled spoon to carefully scoop off any foam that forms on the top of the jam. If you have a candy thermometer cook until the temperature reaches 230 degrees. I actually like my jam a little thinner so I turned off the heat at 215 degrees. If you don't have a thermometer, you can drop a teaspoonful of the jam onto the chilled plate. Give it a minute to see if it thickens up. If it does you are good to go! If it runs, cook a bit longer and test again. Remember to put the plate back into the freezer.
Remove the pot from the heat and allow the jam to cool until just warm. Ladle into freezer safe jars. Store one in the fridge and keep the rest frozen until you need them.