1. In a large bowl, combine warm milk and yeast. Whisk in eggs. Add sugar, 1/4 teaspoon salt. Gradually add flour and whisk until smooth.
2. Place the mixture in a warm place and leave there for 15-20 minutes.
3. In a pot, combine water and beer. Add sausages and bring to a boil. Season with salt, reduce heat, cover and cook for 30 minutes.
4. While the sausages are cooking, let's make crepes. Heat a lightly oiled skillet over medium heat. Pour or scoop the batter onto it, tilting the pan with a circular motion so that the batter coats the surface evenly. When the bottom is light brown (after about a minute or less), loosen crepe with a spatula, flip and cook the other side. Repeat the process with the rest of the batter.
5. Remove sausages from the pot and cut into pieces.
6. In a large skillet, heat butter over medium heat. Saute onion until tender (for about 7 minutes). Stir in flour. Gradually add water-beer mixture, constantly stirring until smooth.
7. Add sausage pieces to the sauce and cook for another 5 minutes. Stir in sour cream, season with parsley or dill (optional) and turn off the heat.
8. Eat crepes with sausages dipping in machanka sauce.