Add the boiling water to a heatproof bowl with the lemon and ginger tea bags. Leave to brew for a few minutes. Add the sultanas, cranberries and dried apricots to the tea, then leave to infuse for a few hours, or preferably overnight.
For the date purée, add the dates to a saucepan with the cold water. Bring to the boil, then remove from the heat and leave to soak for at least 30 minutes; leave to cool. Blend the dates to a purée in a food processor. Once the dates are smooth, add the yoghurt, lemon zest, eggs, flour, ground ginger and bicarbonate of soda. Blend to combine, but avoid over-processing. Preheat the oven to 160oC/Gas Mark 2. Grease and line a 900g (2lb) loaf tin.
Drain the dried fruit of any tea that has not been absorbed, then fold through the cake batter using a large metal spoon. Transfer the mixture to the tin, then bake in the centre of the oven for 1 hour- 1 hour 10 minutes. The cake is cooked when a skewer inserted into the middle comes out clean.