Goulash with mashed potatoes

Goulash like in a canteen in Soviet times INGREDIENTS: • meat - 500 grams • onion - 1 piece • tomato paste - 2 tablespoons • flour - 2 tablespoons • cold water - 300 milliliters • salt • pepper • sugar • potatoes - 1 kilogram • butter - 50 grams • milk - 50-100 milligrams • parsley