Cook the eggs: place in warm water, bring to a boil and from that moment count 5 minutes. Drain, pour over cold water, crack the shells and leave in the water for a moment, then peel.
Peel the cooked beets if unpeeled and dice them. Season with salt and pepper.
Rinse the lamb's lettuce and dry it, place in a salad bowl. Add the beets, chopped feta, diced avocado (drizzled with lemon juice) and egg halves.
Garnish with cress or dill and drizzle with the sauce: mix all the sauce ingredients in a bowl (if using a creamy cheese like favita, add a tablespoon of it to the sauce; if using a crumbly cheese, skip this addition in the sauce).