Peel the potatoes and cook in salted water until done. Strain and leave to evaporate. Peel and finely slice the garlic. Season the fish fillets with salt and pepper. Finely chop the chives, mix well with 250g sour cream and season with salt and pepper. Mash the potatoes and 250 g sour cream and stir until smooth. Season with salt. Heat the oil in a large pan and slowly fry the garlic until crispy, remove and set aside. Fry the fish fillets on both sides and serve with the potato cheese. Garnish the potaotes cheese with caviar, place the garlic on the fish and sprinkle everything with dill. Serve with chive cream.