bring the 2 1/2 cups of water to a boil in a small saucepan
add barley, return to boil, reduce heat, cover and cook for 40 minutes, do not let it boil dry or boil over
heat the butter in a dutch oven over medium heat, add onions, cook five minutes
meanwhile clean the mushrooms and slice
after five minutes add the sliced mushrooms to the onions, add the paprika and dill weed
cover and cook 15 minutes stirring occasionally then stir in the vinegar
slowly sprinkle the flour in and stir to combine, cook and stir for five minutes
add the 3 cups water, cover and simmer 10 more minutes, stir often
reduce the heat to medium low and whisk in the milk, drain the barley and it add to the soup, stir to combine
measure out the sour cream to a small bowl, add a scoop of soup and stir to combine and then pour the whole thing back in the pot of soup, heat slowly over medium low heat, do not let it boil or it may curdle
taste and add salt and pepper as needed
serve warm