The 酉 radical depicts an ancient narrow-necked wine jar. It anchors 酱 in the realm of fermentation — soy paste, sauces, and pickles all share the same fermenting-vat tradition as wine. Same radical in 酒 (wine), 醋 (vinegar), 酸 (sour), 醒 (sober).
Top-left — together with 夕 it forms the phonetic cluster of the simplified 酱 (replacing the traditional 將 of 醬). The pair 丬+夕 supplies the jiāng→jiàng sound; same shape appears as the left side of 将 (jiāng), 浆 (jiāng), 牆 (qiáng).
Top-right — pairs with 丬 to complete the phonetic top half. The 'evening' meaning of 夕 isn't relevant here; in 酱 it's purely a sound-shape that, combined with 丬, evokes the jiāng family.
