Wash the strawberries and remove the leaves. Use a paring knife to cut out the firm white top and center of the strawberries, called hulling.*
Place the strawberries in a large bowl or a Dutch Oven.** Using a potato masher, mash the fruit until you reach the consistency you like. Alternatively, you can puree them in a processor or blender for a finer consistency.
Cut the stems off the jalapeños. Cut the jalapeños in a few large chunks and add them to a mini processor or blender. Coarsely process then add the 1 tablespoon of water. Continue to process until finely pureed.
Measure out the sugar in a separate bowl and set aside.
Place the strawberries and jalapeños in the Dutch Oven and place it on the stove over high heat. Add the pectin and stir well. Add in the butter to reduce foaming.
*You can buy a strawberry huller on Amazon to make this step easier. I have a link in the post for the one I have.
**I like to use my Dutch Oven or a stock pot for this. Since I cook the jam in the Dutch Oven, this eliminates one step and one less item to wash.
***The time will vary based on altitude. The pectin comes with a chart on the instruction.
Use Pectin. I know there are those who don't like to use pectin. In my opinion, it's the way to go. I like to use Sure Jell in the yellow box. I have a link in the post to get it on Amazon.
Don't Reduce the Sugar. It is crucial that you use the exact amount of sugar the instructions call for. You cannot reduce it or increase. Otherwise, the jam will not set up properly.
Start the Canner First. Time is of the essence with Jams. Since the canner uses a large amount of water, and you need to sanitize the jars, lds, and rings, you need to start heating up the water before doing anything with the strawberries.
Cover the Canner. This little step help the water boil faster.