Knead the sourdough in the package a little with your hands. Mix all flour, yeast and salt in a large mixing bowl. Add 600 ml lukewarm water and sourdough and knead to a smooth dough with the dough hooks of the hand mixer. Let the dough rest in a warm place for about 15 minutes. In the meantime peel apples, quarter them and cut out the core. Dice apples finely.
Melt lard at low heat, add apples and simmer at low heat for about 5 minutes. Remove from the stove. Add fried onions, except for 1 teaspoon for sprinkling, mix in and pour into a bowl. Halve the dough and knead again. Form one half into a loaf (approx. 18 cm Ø) with floured hands. Score the surface with a knife in a star shape. Put the second half of the dough into a greased box form (1.25 litre capacity, 25 cm long, 11 cm wide and 7 cm deep) and carve lengthwise with a knife. Put the loaf of bread and the tin on a baking tray lined with baking paper. Cover and leave to rise in a warm place for about 45 minutes. Then bake in the preheated oven (electric cooker: 225 °C/ convection oven: 200 °C/ gas: level 4) for approx. 15 minutes on the bottom shelf. Then reduce the temperature (electric oven: 175 °C/ convection oven: 150 °C/ gas: level 2) and bake for another 45-50 minutes. Remove from the oven.
Put the loaf of bread and the tin on a baking tray lined with baking paper. Cover and leave to rise in a warm place for about 45 minutes. Then bake in the preheated oven (electric cooker: 225 °C/ convection oven: 200 °C/ gas: level 4) for approx. 15 minutes on the bottom shelf. Then reduce the temperature (electric oven: 175 °C/ convection oven: 150 °C/ gas: level 2) and bake for another 45-50 minutes. Remove from the oven. Turn out the tin loaf from the tin. Put the breads on a rack and let them cool down. Sprinkle lard with 1 teaspoon of fried onions and serve with the bread
2 3/4 hours waiting time