Cook the potatoes in a large saucepan filled with salted water for 20-30 minutes until cooked through. Drain and keep warm on the side.
Heat the oil in a sauté pan over a medium heat, and add the minced beef.
Sauté for 3-4 minutes until browned. Remove from the sauté pan and set aside.
Still over medium heat in the same sauté pan, add butter, mushrooms, onions and garlic and sauté for a further 2-4 minutes until browned. Return the browned minced beef .
Next flambee the meat with the brandy or cognac if desired.
When the flame dies down, add the stock, mustard, smoked paprika, salt and pepper.
Stir and simmer with a lid for a further 4-8 minutes over medium / low heat.
Remove from the heat and stir in the crème fraiche and add the chopped gherkins and herbs.
Serve immediately with the boiled potatoes.