Put the dried fruit, sugar and cold tea into a bowl to soak for 1 hour. Preheat the oven to 180 C, 160 C fan, 350 F, gas 4. Prepare the muffin tin - brush the base and sides with melted butter, then coat with polenta, shaking off any excess. This stops the buns sticking to the tin and avoids the use of muffin cases, which can sometimes stick too. You can do this an hour ahead and leave the tin in the fridge.