Peel, wash and chop the potatoes. Cook in salted water for about 15 minutes
Wash the fillet if necessary and dab dry. Fry in 1 tablespoon of hot oil over medium heat for 3-4 minutes. Season with salt and pepper. Take out, wrap in foil and let rest
Clean, wash and dry lettuce leaves and pluck them smaller. Wash and quarter tomatoes. Distribute both on 4 plates
Drain the potatoes and mash them finely with a fork. Mix with broth and vinegar. Whip 2-3 tbsp. oil vigorously into the mixture. Season to taste with salt and pepper
Cut the meat into very thin slices and arrange on the salad. Spread the potato vinaigrette over it. Garnish with pink berries if desired