Orange or tangerine fizz

Peel 18 large oranges (or 24 tangerines), cut with transverse slices (removing all grains), mash in a ceramic dish with a large wooden spoon. Pour warm boiled water, cover with gauze, let stand for a day in the sun. Then strain, add 800 g of sugar, stir, put in the sun. When the fizz begins to roam, pour into bottles, adding 2-3 zest and orange zest to each. Close tightly, store in cold (horizontal position).