Soup is essential in Chinese meals, often served throughout the meal rather than as a starter. In Cantonese cuisine, slow-simmered soups (老火汤) are a daily staple.
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汤 is also a surname, read Tāng (Ming playwright 汤显祖). In classical texts it has a reading shāng used in 汤汤, describing mighty rushing water; modern Chinese keeps only tāng for 'soup, hot water.'
Three-drops water on the left, the indexing radical, declaring 汤 a liquid. Originally it named hot water specifically, so the radical works hand in hand with the meaning. Same family as 河 (river), 海 (sea), 洗 (wash).
Right side is a contracted form of 昜 (the old graph of 阳, sun rising over the horizon). It supplies the sound (yáng to tāng with an old initial drift) and adds heat imagery fitting hot water. Standalone 昜 has nine strokes; here it is reduced to three. Same phonetic family: 场, 扬, 肠.