Peel potatoes, cut longitudinally into quarters and then across into 1.5 cm pieces. Peel onion and cut into small cubes. Crush garlic, peel and grind. Cut mushrooms into medium slices. Heat oil with a 1 cm layer in a large deep frying pan. Put mushrooms and fry for 5 minutes. Add onion and continue to fry for 10 minutes stirring. Add potatoes and garlic, stir, cover with a lid and slack the fire to the minimum. Simmer for about 25 minutes until soft potatoes. Sprinkle with chopped dill before serving.