Place the whole lemon in a small pot of water. Bring to a boil and simmer for 6 minutes to soften the rind and remove bitterness.
Remove the lemon, let it cool slightly, then slice it open. Carefully remove all seeds (this is crucial to avoid bitterness).
Preheat your oven to 160°C (325°F) and grease your 35x15 cm loaf pan with 1 teaspoon of butter.
Put the deseeded lemon slices into a blender or food processor. Blend until you get a completely smooth, creamy lemon paste.
In a large mixing bowl, whisk the eggs and sugar together until the mixture is pale and frothy.
Pour in the milk and vegetable oil, and whisk to combine. Add the blended lemon puree and stir well.
Sift in the flour and baking powder. Using a spatula, fold the ingredients together gently until just combined (do not overmix).
Gently fold in the mixed dried fruit.
Pour the batter into the greased loaf pan. Bake for 30 to 35 minutes at 160°C (325°F). Check with a toothpick; it should come out clean. Let cool before slicing.
