Peel and wash the potatoes and place them on a baking tray lined with baking paper. Wash the rosemary and dab dry. Pluck needles from the stems, except for a few for garnishing, and chop them coarsely. Drizzle potatoes with 1 teaspoon of oil. Sprinkle with rosemary and sea salt. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for about 40 minutes.
Wash the zucchini, rub dry and cut into 5 mm thick slices. Clean and trim the mushrooms. Clean, wash and dry grate the tomatoes. Wash shrimps and pat dry. Heat 1 teaspoon of oil in a pan. Brown the zucchini slices on both sides. Take them out and let them drip off on kitchen paper. Place the zucchini slices on skewers in a wavy shape, skewering a mushroom, shrimp or tomato between each turn. Season with salt. Fry skewers in cooking fat for 2-3 minutes on each side. Bring condensed milk to the boil, stir in stock and saffron. Add wine, bring to the boil again until the sauce has thickened slightly.
Take them out and let them drip off on kitchen paper. Place the zucchini slices on skewers in a wavy shape, skewering a mushroom, shrimp or tomato between each turn. Season with salt. Fry skewers in cooking fat for 2-3 minutes on each side. Bring condensed milk to the boil, stir in stock and saffron. Add wine, bring to the boil again until the sauce has thickened slightly. Arrange everything on plates and garnish with rosemary. Sprinkle with saffron threads if desired