1) Harvest 1 cup of nasturtium seedpods from the base of the stems when they’re still young, tender, and green. (Mature seeds, which are bitter, often have red or black spots.)
2) Combine 1 teaspoon salt and 1 cup filtered, room-temperature water to make a brine. Fill a pint-size mason jar with the seeds and 1 tablespoon each of garlic, dill, and whole peppercorns. Pour the brine over the “capers.”
3) To keep seeds submerged, place a sandwich bag on top of the jar opening and fill it with water. Store undisturbed in a dark place for 5 to 7 days. Replace the bag of water with a lid and refrigerate.