First, make a strong decoction by combining the dried elderberries with water and any other additional spices, citrus zest and herbs (coarse, not delicate) in a saucepan, cover and bring to a boil, then reduce to a simmer for 20 minutes, reducing the liquid by half.
Remove the decoction from heat and take off the lid, let stand and steep for a further 30 minutes. If you want to add a small amount of delicate complementary herbs (leaves, flowers) the add them here (I used olive leaf - another great anti-viral).
Once cooled, set a funnel over a pyrex jug, and strain out the mixture using a cheesecloth. Press the cheesecloth tightly to extract every last drop, then discard or compost the plant material.
To the pyrex jug, add honey - half the volume of liquid for a thinner syrup, and equal the amount for a thicker but sweeter syrup. Place the jug in a saucepan filled with a little hot water, stir well over low heat to dissolve the honey fully.
Pour syrup into a sterilised glass jar with a tight fitting cap/cork, shake well, label, date, and store in the fridge.
Dosage: up to one tablespoon a day for adults, increasing to three tablespoons maximum if fighting a cold. For small children, 1/2 a teaspoon a day is adequate, increasing to 1/2 teaspoon three times daily if sniffly. For older children, 1 teaspoon daily, increasing to 1 teaspoon three times daily as needed.