Great dolloped on top of a sandwich, smeared on a toasted baguette with creamy goat cheese or added to the top of an arugula salad drizzled with olive oil.
½ pound spring onions, about 1 bunch
½ cup apple cider vinegar
¼ cup water
3 tablespoons sugar
1 teaspoon sea salt
1 teaspoon mustard seeds
½ teaspoon celery seed
½ teaspoon peppercorns
pinch red chili flakes