Sarson da saag (also sarson ka saag or mustard greens) is a popular Punjabi vegetarian dish consisting of leaves of the mustard plant, spinach, green chilli, fenugreek, ginger and salt. The dish is slowly simmered in its own juices over low heat until it develops the typical, buttery creaminess.
In Punjab, it is topped with fried onions and fresh homemade butter. In Uttar Pradesh, however, the dish is topped with yogurt and tomatoes to slightly reduce its bitter and peppery taste. Due to the pungency of mustard leaves, broccoli, radish and turnip are sometimes added to enhance the flavors.