Preheat oven (electric cooker: 200°C/circulating air: 175°C/gas: level 3). Coat a baking tray (approx. 35 x 40 cm) thinly with oil. Place baking paper flat on top and heat the baking tray in a hot oven for 4-5 minutes.
Mix eggs, milk, mineral water, 1 tablespoon of oil and flour to a smooth dough. Season with about 1/2 teaspoon salt. Pour the dough onto the hot baking tray and
Meanwhile, wash the orange hot, dry it and finely grate half of the peel. Squeeze this half, cut the other half into slices. Mix peel, approx. 2 tbsp. juice, sour cream and mayonnaise.
Season with salt, pepper and 1 pinch of sugar. Clean, wash and dry lettuce.
Remove the baking tray from the oven and pull the crêpe from the baking tray together with the baking paper. Spread the crêpe with orange cream, leaving a rim of approx. 2 cm all around. Cover with salad leaves and smoked salmon.
Roll up crêpe and cut into slices. Garnish with the orange wedges.