Place the cut kumquats in a pot and cover them water, one inch above the fruit. Over medium heat, bring the kumquats/water to a gentle boil. Once you've reached a boil, lower the heat and simmer for 30 minutes. Drain and place kumquats in a glass jar.

Meanwhile, add sugar, vinegar, peppercorns and salt in a pan and gently heat over medium/low heat. Stir gently and cook until sugar has dissolved (2-3 minutes). Carefully pour sugar/vinegar mixture over kumquats in the glass jar. Cover with the lid and place in the fridge to cool before using (about 30-60 minutes).

Kumquats will stay fresh in the fridge for 3-4 weeks.