Pat the tuna steaks dry, drizzle with lemon juice, wine vinegar and Wocester sauce. Season the steaks with salt and pepper, sprinkle with the chopped dill and leave to stand in the refrigerator for 10-15 minutes. Heat the butter or margarine in a pan and sweat the finely chopped onion in it until translucent. Deglaze with red wine, top up with the tomato sauce and cream, add the olives, season with salt, pepper and sugar. Put the tuna steaks in the sauce and cover and let simmer for 20-25 minutes in a preheated oven.