Grease the inside of the glasses slightly to half. Mix eggs and milk. Season well with salt, pepper and nutmeg. Distribute evenly in the glasses. Place in a shallow, very wide pot, pour boiling water on them, so that the glasses are well half in the water. Cover and let it simmer at low heat for about 20 minutes
Meanwhile peel the onion and dice very finely. Wash, clean, peel and finely dice the beetroot. Heat the oil in a small pan. Cook the onions and beetroot on a low heat for 3-4 minutes while turning
In the meantime, wash the chives, shake them dry and cut them into fine rolls. Sprinkle beetroot with sugar, deglaze with vinegar, bring to the boil briefly and season with salt and pepper. Remove from the stove, let it cool down a little. Mix in about 3/4 of the chives
Carefully lift the egg pit glasses out of the pot. Rub glasses dry on the outside. Pluck the fish. Spread beetroot and fish evenly in the glasses, sprinkle with remaining chives