Gather the ingredients for your peach jalapeno jam.

Peel and slice the peaches. Remove their pits.

Place the peach slices and sugar in a non-reactive pan. Let them sit for an hour or two until the peaches are soft and the sugar has dissolved.

Sterilize the jars and lids with your preferred method.

Place a plate in the freezer. We'll use this later to test the jam if it's ready. Alternatively, you can just freeze a metal spoon for 10 minutes.

Add the lemon juice and diced jalapenos to the peaches. Bring to a boil over high heat, then reduce the heat to low and stir occasionally. Don't mind the foam that rises to the top of the jam; it's up to you whether you want to skim it for a clearer jam.

After 40 minutes, test the jam to see if it's ready. Spoon some of your peach jalapeno jam on the frozen plate or spoon. If it still runs, continue cooking the jam for 5 minutes, stirring occasionally.

Your peach jalapeño jam is ready when it no longer runs on the frozen plate.

Pour the jam into the hot, sterilized jars, leaving some space at the top. Cover the jars with their lids and rings, then cool them before refrigerating.