1. Buttermilk is a great substitute for the eggs in the doughnuts
If you do not have buttermilk, then just add 2 teaspoons of lemon juice or vinegar to ¼ cup ( 60ml) milk. Allow standing for 5 minutes before adding to the recipe in place of eggs or buttermilk.
2. The water, milk and mashed potatoes should be warm. Not too hot or cold as this will affect the yeast. The right temperature ensures that the dough rises well