Knead butter, fried onions, lemon juice and pepper and form into a roll. Wrap butter in foil and chill. Peel, wash, halve and cut carrots into pieces. Peel and finely chop the onion. Heat 1 tablespoon of oil in a pot .
Sauté onion and carrots. Add stock, bring to the boil and cook for 12 minutes. Wash the basil, put some aside for garnishing and remove the leaves. Cut leaves into fine strips. Heat 2 tablespoons of oil in a grill pan. Fry the steaks on both sides for about 2 minutes. Remove and season with salt and pepper. Add basil to the carrots. Season to taste with salt and pepper. Cut the fried onion butter into slices.
Remove and season with salt and pepper. Add basil to the carrots. Season to taste with salt and pepper. Cut the fried onion butter into slices. Arrange carrots, steaks and the butter on a plate. Garnish with basil. Serve with mashed potatoes