Stir tomato paste, sour cream and orange juice until smooth. Season to taste with salt, pepper and some Tabasco
Chop the onion finely. Rinse crabs briefly and dab dry with kitchen paper. Whisk eggs and mineral water. Season with salt and pepper
Heat the oil in a small coated pan. Sauté the onion in it while stirring until transparent. Add egg milk and add the crabs. Let the egg fry at low heat, pushing it together more often with the spatula towards the middle.
Toast bread golden brown roast. Wash the lettuce leaves, shake dry and place on the toasts. Spread prawn scrambled eggs and sauce on top. Garnish with parsley