Take 4lbs ripe blackberries. Wash them well, put them into a polythene bucket and crush with a potato masher. Pour over it 1 gallon boiling water. Stir well, and allow to become lukewarm (about 21 C) then add pectic enzyme (according to instructions), and a day later add the yeast (and nutrient if using). Cover closely and leave for 4 or 5 days, stirring daily. Strain through nylon netting on to 3lbs granulated sugar. Stir well to make sure that it is all dissolved. Pour into a fermentation jar, filling to the shoulder, and fit an airlock. Keep the spare liquor in a smaller bottle also fitted with a trap or plug of cotton wool. When the ferment quietens sufficiently for there to be no risk of it foaming through the trap (after about a week) top up with the spare wine to the base of the neck. Refit the trap, leave it til it clears, then rack.
It's very very nice...