Begin with making the brine. Place 1 litre (4 cups) water in a stockpot. Add the lemon, thyme, salt, brown sugar, caster sugar and peppercorns. Bring to a boil over high heat, stirring often to ensure all sugar dissolves. Remove from the heat. Stir in 2 litres (8 cups) water. Place in the fridge and cool to below 4°C on a cook’s thermometer.