Prepare your gear. Rinse berries, sterilize a jar or two, and have a small plate in the freezer for the gel test. Ready? Let’s roll.
Cook the berries. In a heavy pot, mash the berries slightly and bring to a simmer. Stir occasionally so nothing sticks or scorches.
Add sugar and vinegar. Sprinkle in sugar and pour in the vinegar. Stir until the sugar dissolves and the mixture comes back to a gentle boil.
Control the heat. Add the chopped peppers and a pinch of salt. Simmer 5–10 minutes, until the berries break down and the flavors mingle. Taste and adjust heat if needed.
Test for set. If you want a firmer jelly, stir in pectin and simmer a couple more minutes. For a looser jam, skip it. Do the spoon test on a chilled plate: if it wrinkles, you’re good.
Fill the jars. Remove from heat and skim off any foam. Ladle the hot jelly into sterilized jars, leaving a little headspace. Seal and let them cool undisturbed.