– 1 tbsp butter – ½ tbsp mild olive oil – 600 g (approx. 20 oz) pork loin (tenderloin/ pork fillet) sliced into strips – 6 shallots or 1 medium onion, finely diced – 60 ml (¼ cup) vermouth , cognac or dry white wine – 100 g (1 cup) chestnut mushrooms , sliced – 100 g (1 cup) white button mushrooms , sliced – 2 cloves garlic minced – 1 tbsp tomato paste – 2 tsp English mustard or 1 tbsp Dijon mustard – 2 tsp smoked paprika (or regular mild paprika) – 1 tsp salt – 120 ml (½ cup) mushroom or chicken stock – 240 ml (1 cup) sour cream – 1 tbsp dried parsley – 1 tsp dried dill or you can use fresh