Put 1/2 cup warm water in a large bowl (of a stand mixer, if you have one) sprinkle over a pinch of the sugar and the yeast; let stand for 5 minutes, or until foamy.
Meanwhile, in a small saucepan heat the milk, butter, orange zest and remaining sugar until the butter melts. Set aside and cool slightly, then add to the yeast mixture along with half the flour and the eggs. Beat by hand or with the paddle attachment until well blended and gooey.
Attach the dough hook and add another 1 1/2 cups of flour and the salt, and mix/knead for 7-8 minutes, until you have a smooth, tacky dough that comes away from the sides of the bowl. Add a little extra flour if you need it, but don't add too much - it shouldn't be sticky, but should be tacky. Cover with a tea towel and let rest for 1 1/2-2 hours, until doubled in bulk.
On a lightly floured surface, roll the dough out into a 14x18-inch rectangle. Brush with almost all the butter (leave a bit for brushing on top) and sprinkle with brown sugar and cinnamon, scatter with currants, candied citron and dried cranberries; drizzle with honey or maple syrup.
Starting on a long edge, roll up jelly-roll style. Using a sharp serrated knife, cut the roll crosswise in half, then cut each piece in half, making quarters. Then cut each quarter into three pieces, so you have 12. Butter a muffin tin or spray it with nonstick spray, or put a square of parchment in each.
Place one roll in each muffin cup, cover the pan with a tea towel and let rise for another hour. (Alternatively, but them into the fridge to slow the rise overnight.)
When you're ready to bake, preheat the oven to 375°F. Brush the tops of the buns with the rest of the melted butter and bake for 25-30 minutes, until golden. Remove from the pan while they're still warm.