Peel and finely chop the onion. Wash the coriander and shake dry, put some leaves aside for garnishing. Heat 1 tablespoon of oil in a saucepan. Fry the onion in it. Add the rest of the coriander and stems and steam briefly.
Add 400 ml water, cream and frozen peas and bring to the boil. Stir in wasabi. Season with salt, pepper and 1 pinch of sugar. Simmer covered for about 10 minutes.
Meanwhile peel the shrimps down to the caudal fin and cut them lengthwise on the back. Remove the dark gut. Wash the shrimps and dab them dry.
Remove soup from the stove and puree very finely with a hand blender. Season to taste and keep warm.
Heat 2 tablespoons of oil in a frying pan. Fry the prawns for 3-4 minutes while turning. Season with salt and pepper. Serve the soup in glasses. Garnish with one shrimp and the remaining coriander.