Sour-sweet is a term that describes a particular taste that is a mixture of both sour and sweet flavors. To describe flavors that are similar to sour-sweet, some synonyms you can use are tart, tangy, zesty, piquant, and appley. Tart implies a sharp and biting taste that is slightly bitter, whereas tangy has a more pungent and sharp taste that has a hint of sweetness. Zesty has a more citrusy and slightly bitter taste that is still refreshing, while piquant has a spicy and lively flavor that is sharp and tangy. Appley, on the other hand, refers to a sweet and slightly acidic taste that is similar to the taste of apples.