Onion Gothsu is a traditional South Indian side dish made with onions, tomatoes, and a blend of spices. It has a tangy and slightly sweet flavor, making it a perfect accompaniment to idli, dosa, or pongal. The onions and tomatoes are cooked until soft and then tempered with mustard seeds and curry leaves. This dish is easy to make and can be stored in the refrigerator for a few days.