Wash and halve the potatoes. Put potatoes on a baking tray, drizzle with 2 tablespoons of oil, season with salt. Cook in the preheated oven (electric cooker: 200 °C/ circulating air: 175 °C/ gas: level 3) for 35-45 minutes.
Peel the onions. Finely dice 1 onion, cut the other into slices. Peel, wash and chop ##carrots## and ##celery##. Clean, wash and chop the ##leek##.
Heat 1 tablespoon of oil in a frying pan. Sauté diced onions for 1-2 minutes. Add minced meat and fry until crumbly. Stir in tomato paste and fry for about 2 minutes. First add ##vegetables## and deglaze with broth about 1 minute later.
Add tomatoes and season with salt, pepper and paprika. Let the sauce thicken for about 15 minutes at medium heat. Meanwhile clean and wash the rocket and drain well. Wash, clean and slice the tomatoes.
Mix tomatoes, onion rings, vinegar and olive oil and season with salt, pepper and a little sugar. Mix in the rocket shortly before serving. Grate cheese. Season sauce again and spread it on the potato halves.
Sprinkle with cheese and gratinate under the grill for about 5 minutes. Arrange 2 potato halves and salad on plates.