Wash the clementines and pierce a few holes in the skin with a cocktail stick or fine skewer. Place in a large saucepan, add the bicarbonate of soda and cover with water.
Bring to a boil and boil for 12 minutes. Drain.
Tie spices in muslin. Add vinegar and spices to drained clementines in pan. Cover and simmer for 20 minutes.
Remove spice bag and add sugar and stir gently until dissolved. Simmer for further 20 minutes in covered pan.
Using a draining spoon, lift the fruit gently and place in sterilized jars. Continue to simmer the liquid for 10 minutes. Cool slightly and pour over fruit. Seal the jars and store in a cool place.