Creamy beetroot soup ala Baltic style

The flu decided to mess with me, and kept me in not so good mood for some days. With the sun shining is not so bad, but my energy level is halved, to say the least.
I baked fresh bread and promised accompanying fresh salad with it for dinner for the family, but maybe because of my flu-ish mood I wanted something warm, something liquid. I think European soups are the best food on Earth for whatever occasion, but especially for somebody sick..
Why European in particular? Because the "soups" here in US are so thick, they remind me of the Hungarian főzelék, which is of course great, it just has nothing to do with soups :).
I bought some, much more than needed, beetroot at the local Sprouts because the organic beetroot bunch was sold for a steal, $3 for 2 bunches, each with 3 tennis ball size beetroot.
I made a huuge amount of soup, but here I share with you the recipe for just a decent sized 4-5 person family.
With Easter coming, it is a food to keep in mind, it is a delicious way to use up all those hard boiled eggs you have left over or your hubby brought home from locsolás :).

Ingredients
2 tennis ball size beetroot
1 similar size potato, preferably the type meant for mashed potatoes
salt, pepper
1 small onion
water
500 ml, half quart natural, unflavored yogurt, I used Bulgarian yogurt
2-3 tbsp oil, use olive oil if you prefer
water, about 1 litre, 1 quart
lemon to taste

Serving

yogurt or sour cream to serve. If you wanna get fancy, and add to the taste, mix some finely grated horseradish in the yogurt/sour cream

hard boiled eggs, at least 1 egg/person
It can be also served with hot boiled or baked potato wedges
rye bread, or white bread, fresh or toasted, whichever you prefer

Peel the potato and the beetroot.
In a medium, about 3 litres, 3 quarts, pot add the oil, chop the onion finely, and over medium heat fry the onions.

Toss in the beetroot and the potato, let it simmer shortly in the hot oil, and add the water, just enough to have the content of the pot, eg. the beetroot and the potato covered. Add salt and black pepper to taste.
Let it simmer on medium heat under a lid, for about 20 minutes, until the potato is soft, and the beetroot is "crunchy"- soft.

Let it cool a little, and in a food processor blend until smooth, at least as smooth as possible..
If you prefer smother taste, choose a less sour yogurt instead of the Bulgarian yogurt. we are a sour-tooth family, I can never add enough vinegar or lemon, so we love the sourness of both the yogurt, and even some extra lemon juice.
Mix in the yogurt, adjust sourness with additional yogurt or and lemon. Serve with the sour cream/yogurt and the hard boiled eggs.
The most wonderful thing about this soup is that can be served hot or cold.
If you choose to serve cold, adds to the harmony of the taste if you serve with hot, fresh boiled eggs (or hot boiled/baked potato wedges), but don't stress about it, they are good cold as well.
Enjoy!