For the sushi rice, wash the rice until the water is clear, then drain. Carefully bring to the boil with 1⁄4 l water in a pot. As soon as the rice boils, close the pot with aluminium foil and a lid.
Cook at low heat for about 10 minutes. Cover and leave to swell for a further 10 minutes on the switched-off hotplate. Heat the vinegar, sugar and salt until the sugar has dissolved. Place the rice in a large bowl.
Drizzle vinegar mix over it and fold in with a moistened wooden spoon. Let the rice cool down a bit, but process it as warm as possible.
For the Tempura dough, mix 100 g Tempura flour, egg yolk and 1⁄4 l cold water. Do not stir too hard, the dough may be a little lumpy. Put it in the fridge, then it will be nice and crispy when baked out.
Wash the asparagus and cut the ends off generously. Cook in little water for 2-3 minutes. Lift out and drain well. Rinse shrimps, dab dry and remove the dark gut if necessary. Put 3 prawns on 1 skewer each.
First pull through the tempura dough, let it drip off a little and turn it in the panko crumbs.
Heat the oil in a wide pot to approx. 180 °C (it is hot enough as soon as bubbles rise from a long wooden skewer) or in a deep fryer. Fry the prawn skewers one by one for 3-4 minutes, turning them from time to time.
Drain on kitchen paper.
Line a bamboo mat with cling film. Place 1 nori leaf on the bamboo mat with the rough side facing upwards. With moistened hands about 1⁄4 Sushi rice crosswise on 2⁄3 of the leaf loosely thinly distribute.
Place about 1⁄4 of the radish and 1 asparagus stick in the middle of the rice. Drizzle 1 strip of mayonnaise and sweet and sour sauce over each. Put 1 prawn skewer on top. Roll up firmly using the bamboo mat. Do not wrap up the foil.
Pull out the skewers. Form 4 rolls in this way. Cut sushi rolls into 6-8 pieces. Add wasabi, soy sauce and sushi ginger.