Peel and wash the potatoes. Clean, wash and halve the mushrooms. Cut bacon into pieces and fry until crispy, then put aside. Heat oil in the bacon fat. Fry the potatoes and mushrooms for 5 minutes, turning them over. Season with salt and pepper.
Stir in tomato paste. Deglaze with stock, bring to the boil and stir in soup powder. Cook at medium heat for another 10 minutes. Fold in sage. Add bacon again. Serve sprinkled with parmesan