Place the diced strawberries, peaches, finely diced jalapeno pepper, sugar and lemon juice together in a large cast iron skillet over medium heat.
Cook, stirring often, until the strawberries, peaches and liquids have reduced down to a thick jam, about 20-25 minutes. It’s done when a spoon pulled through the jam leaves a path in the skillet.
Pour into a glass jar and allow to cool. Cover with a tight lid and store in the refrigerator for a week. Enjoy.