Pour lemon juice over the prawns and let them soak for 10 minutes. Clean and wash spring onions and cook them in a wide pot with boiling salted water for 8-10 minutes. In the meantime wash parsley and dill, dab dry and chop finely.
Mix the creme fraiche and milk until creamy and season to taste with salt and pepper. Stir in the herbs and prawns, except for a little for garnishing. Drain spring onions well and arrange in an oblong dish.
Add some crab cream-fraîche and sprinkle with the remaining crabs. Grind a little fresh pepper on top and serve garnished with lemon wheels and lemon balm. Remaining crab-crème-fraîche extra rice
Wholemeal bread tastes good with it.