List of sour soups

Sour soup
Spicy sour soup flavoured with tamarind, dried shrimps, and salted soy beans
Type	Soup
Variations	Many

Various sour soups, named for their characteristic sour taste, are known in various East Asian, Southeast Asian, and the cuisines of Eastern Europe.

Asian origin

Samlar machu, a Khmer term for a category of sour soups.
Canh chua (literally "sour soup") is a sour soup indigenous to the Mekong River region of southern Vietnam.
Sinigang, Philippine sour soup
Hot and sour soup
Tom kha kai
Tom yum
Lemon rasam - an Indian sour soup made with lemon juices
Dunt dalun chin-yei - drumstick sour soup (cuisine of Burma)
Sayur asem
Ikan kuah kuning - an Indonesia sour fish soup
Sour soup fish - a Guizhou cuisine in southern China

Beet borscht cooked in Eastern Europe has appreciable sour taste due to adding sour beet (or fermented beet juice) or sour cream.
Borschts without beets are sour in general
Kapusniak, Ukrainian and Polish soup made from sour cabbage (sauerkraut), millet and potatoes in meat broth
Sour shchi, a sour cabbage soup in Russian cuisine
Rassolnik, traditional Russian soup made with pickled cucumbers
Sorrel soup
Solyanka, thick, spicy and sour soup in the Russian and Ukrainian cuisine
Okroshka, cold Russian soup traditionally made with kvass
Sour rye soup, known as żur in Belarus and Poland, or kyselo in Slovakia and the Czech Republic.
Jota (Slovenian cuisine)
Styrian sour soup (Slovenian cuisine)
Vipava sour soup (Slovenian cuisine)

Borș, term from the historic region of Moldavia for sour soups or fermented wheat bran, essential ingredient to cook Ciorbă.