Peel and finely chop the onion. Knead minced meat with onion, paprika, 1 egg, breadcrumbs, mustard and oregano. Season with salt and pepper. Sprinkle a thin layer of breadcrumbs on a work surface. Roll out the minced meat into a rectangle (28 x 30 cm).
Cut the bark off the gouda. First chop the gouda, then put some ham on top. Leave a 2 cm margin each time. Roll up from the long side. Fold in open ends and press together.
Place on a baking tray lined with baking paper. Peel and wash the potatoes. Roughly grate potatoes and mix with 2 eggs. Season with salt. Spread half of the potato mixture on the chopping roll and press on.
Chill the rest of the potato mixture. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for 50-60 minutes. Cover if necessary after 40 minutes. Clean and wash the salad and drain well.
Wash, clean and slice the cucumber. Wash, clean and halve the tomatoes. Whisk vinegar, salt, pepper and sugar in a bowl, stir in 5 tablespoons of oil in a thin stream. Season to taste again.
Heat 3 tablespoons of oil in a frying pan. Add the rest of the potato mixture in portions with a tablespoon to the oil, press to flat Rösti. Fry for 2-3 minutes, turning once to golden brown Rösti, keep warm.
Mix the salad ingredients, sprinkle with the vinaigrette. Serve the chopped roll with the rösti and salad.