Place the flour,½ tsp salt, caraway seeds and yeast in a large bowl. Make a well in the centre and pour in the melted margarine and 200ml warm water. Mix to combine all of the ingredients, adding more water or flour if needed, then knead for 2 mins to form a soft dough. Place in an oiled bowl, cover with cling film and leave in a warm place to rise for 1 hr.
Once doubled in size, knead the dough for 1 min, then divide the mixture into 12 balls. Cut each ball in half and roll each piece into a thin sausage shape. Twist the 2 pieces together, then join the ends to form a circle. Place on a lightly greased baking tray, cover with a tea towel and leave to rise again for 30 mins.
Heat oven to 200C/180C fan/gas 5. Brush the biscuits with a little beaten egg and bake for 10-15 mins until golden. Remove to cool on a wire rack, then turn the oven down to 110C/90C fan/gas 1a„4. Once cool, return the biscuits to the oven and bake for a further 10 mins, then turn off the heat completely, leaving the biscuits in the oven to dry out for 2 hrs.