Wash liver, pat dry. Sprinkle with pepper. Place slices of bacon on top, roll up and pin with wooden skewers. Fry liver rolls in hot fat all around. Salt, remove.
Peel onions and cut them into rings. Sauté briefly in frying fat. Add tomato paste, deglaze with vegetable stock. Season with salt, pepper and lemon juice. Let the liver rolls simmer for ten minutes in the sauce at low heat.
Stir the tomato crème fraîche into the sauce stock. Serve with grainy cooked rice mixed with chopped parsley.