Cut the avocados in half and remove the stone. Peel the avocado halves and use a ball cutter to cut out as many balls as possible from the flesh. Use the rest for other purposes. Sprinkle the avocado balls with lemon juice and set aside.
Wash the tomatoes, dab dry and cut in half. Remove seeds and cut the halves into cubes. Peel onions and garlic. Finely dice the onions, press the garlic through a garlic press.
Wash the dill, dab dry and cut finely, except for a little to garnish. Mix yoghurt, dill, garlic and 1/3 of the onions. Season to taste with salt and pepper. Add the prawns, avocados and diced tomatoes to the sauce.
Wash, peel and finely grate the potatoes. Mix in egg, flour and remaining onions and season with salt and pepper. Heat some clarified butter in a frying pan and bake about 12 potato pancakes in portions while turning.
Arrange on small plates or platters with shrimp salad. Serve garnished with dill.