Egg-free, dairy-free cake with tahini

Ingredients

• 1 cup tahini
• 1 cup freshly squeezed orange juice
• 1 cup sugar
• 1 cup water
• 1 cup roughly chopped walnuts, plus a little more for sprinkling
• 1 cup currants
• 1 cup raisins
• 1/2 cup honey or orange marmelade
• 1 (500g) packet self-raising flour
• 1tsp baking soda
• 1tsp cinnamon
• a little bit of cloves
• 250g confectioner's chocolate