In a small mixing bowl, combine yeast with about 1/3 of the warm milk and let stand till it foams, about 10 minutes.
In a large mixing bowl, combine the flour, psyllium, salt, lemon zest and sugar. Add the egg, butter, remaining milk and the yeast mixture. Knead to a smooth dough with the dough hook of a food processor, or by hand on a lightly floured work surface. Place in a greased bowl, cover and let rise 1 hour in a warm place.
Place raisins in a small bowl, and pour over hot water. Let soak till softened, then drain well and pat dry with kitchen roll.
Lay the dried raisins, almonds and mixed peel on a floured surface. Place the risen dough on top and knead in the ingredients. Knead in the rum as well. Form into a loaf shape and place on a greased baking tray. Cover with a clean kitchen towel and let rise for 45 minutes.
Preheat the oven to 200 C / Gas 6. Bake stollen on the middle rack for 1 hour.
Immediately after removing the stollen from the oven, brush with melted butter and dust liberally with icing sugar. Let cool before slicing and serving.
What is psyllium?
Psyllium gives gluten free baked goods texture and body. It is used instead of xantham and guar gums, which can cause digestive problems for some people. Find psyllium powder at health food shops, like Holland & Barrett, or online. The powder is often sold as a colon care item - but don't be alarmed, it'll work wonders in your gluten free baking!