The primary ingredient in the Spanish cold soup gazpacho is tomato. In the best-known Andalusian style, ripe tomatoes provide the soup’s red color, acidity, sweetness, and much of its body.
Gazpacho is traditionally blended with ingredients such as cucumber, green pepper, onion, garlic, olive oil, vinegar, salt, and water. Bread may also be added to create a thicker texture. The mixture is served chilled, making it especially associated with hot southern Spanish summers.
The dish has older roots than the tomato itself: early versions of gazpacho-like soups used bread, olive oil, garlic, vinegar, and water before tomatoes and peppers arrived in Europe from the Americas. That history explains why cucumber, pepper, and onion are important ingredients but are not the primary ingredient in the classic red version. Other regional soups called gazpacho can differ substantially.