Gundruk is a fermented form of broad mustard leaves, yellow mustard, radish, or cauliflower leaves. It can also be cooked with/without potato or soybean. Leaves are sun-dried, washed, and fermented in an earthen jar for about a week. It is taken out of the jar and sun-dried again until it turns crispy and ready for longer period storage. It is considered a classic Nepali preparation, cooked and popular in all strata of people, both in urban and rural cooking. The tradition of preserving green leaves primarily must have been viewed to save excess green for rainy days. It is served with Dhido (corn meal) or rice. In some places, sliced yellow pumpkin is added during the fermentation process so that the soup becomes more tasty and nourishing. Fermentation and sun-drying of greens enhance the nutritious value of vitamin C and D without destroying the original health benefits. It also adds digestive properties and enhances appetite. It is commonly cooked in soupy form and called Gundruk ko jhol. It can also be used to make achar (pickle) by soaking it in water, pounding it to make it soft and mixed with salt, green chili, garlic, and uncooked mustard oil. There is also the practice of preparing it in the form of powdered Chatani or cooking with tomato as an achar with a different taste.
Here is a very common recipe of Gundruk ko Jhol with soyabean (bhatamaas).
1 bowl or big handful Gundruk
½ cup Soybeans (preferred black one)
1 medium size Onion
3 clove Garlic
1 small Ginger
3 medium size Tomatoes
1 tsp Cumin and Coriander powder
½ tsp Turmeric powder
2 Green Chilies
½ tsp Fenugreek seed
½ tsp Mustard seed
Fresh Coriander leaves
2 tbs Pure Mustard Oil (or any vegetable oil)
In the same pot, add a tbs of mustard oil, and sauté a bowl of gundruk for around 2 mins with continuous stirring, until it starts releasing fermented aroma. Transfer the gundruk in other bowl.
In a medium heat, add two tbs of mustard oil in the same pot. Fry fenugreek and mustard seed after oil starts smoking. Add chopped onions, green chilies cut in half and finely chopped/grated garlic and ginger, and fry until light brown. Add turmeric powder and then chopped tomatoes. Add a tbs of salt (or according to your taste and the quantity of soup you are making) and cumin and coriander powder (or you can use curry powder). Add 2 tbs of water and cook until it turns gravy.
Add 2-3 cups of water and bring to boil. Add sautéed gundruk, put the lid on and cook for around 8-10 mins in low medium heat. Turn the heat off, squeeze a lime juice and let it cool down for few mins. Add roasted soybeans in the soup and serve in a bowl. Garnish with fresh coriander leaves. You can just slurp the soup or you can have the soup with steamed rice or bread/roti.