Wash the potatoes thoroughly and cook for about 35-40 minutes (should be nice and soft). Roast pine nuts in a pan without fat, remove. Mix the quark, cream cheese and milk until smooth. Season to taste with salt, pepper and possibly cayenne pepper. Peel and finely dice the onion and garlic. Quarter, core and dice 4 tomatoes. Wash the rocket, shake dry and cut into strips except for something for garnish. Stir the onion, garlic, rocket and diced tomatoes into the quark. Score the remaining tomatoes crosswise, brush with oil. Grill under the hot grill or in the oven at high top heat for 8-10 minutes. Season with salt and pepper. Drain the potatoes, cut in half and fill with a little quark. Scatter pine nuts and the rest of the rocket on top. Serve with the grilled tomatoes and the remaining quark