Sikkim Gundruk Soup Fermented Leafy Green Broth

Ingredients

• 1 cup dried gundruk (buy at Nepali or Himalayan specialty stores — dried fermented mustard or radish greens; if unavailable, substitute with 2 tbsp miso paste stirred into the soup as a fermentation substitute)
• 1 medium potato — peeled and diced small
• 1 tomato — finely chopped
• 2 tbsp oil (mustard oil preferred)
• 1 tsp cumin seeds
• 4 garlic cloves — finely sliced
• 1 onion — finely chopped
• 1 green chilli — slit
• 1/2 tsp turmeric
• 3 cups water
• salt to taste
• spring onions for garnish

Method

1. Soak the gundruk: Place 1 cup dried gundruk in a bowl. Cover with 2 cups warm water. Soak for 10 to 15 minutes until softened. The water will turn brownish and smell sour — this is the fermentation liquid that gives the soup its characteristic sourness. Do not discard the soaking water.
2. Squeeze the gundruk: After soaking, squeeze the gundruk pieces gently to remove excess moisture. Keep the squeezed pieces aside. Reserve the soaking liquid.
3. Heat oil and temper: Heat 2 tbsp oil in a soup pot on medium. Add cumin seeds — wait to crackle. Add finely sliced garlic — fry 30 seconds until golden.
4. Cook onion: Add finely chopped onion. Cook 6 minutes until translucent.
5. Add tomato and green chilli: Add chopped tomato and slit green chilli. Cook 4 minutes until soft.
6. Add turmeric: Turn to low. Add turmeric. Stir 30 seconds.
7. Add gundruk: Add the squeezed gundruk pieces. Stir to combine with the tempered onion-tomato.
8. Add water and soaking liquid: Add 3 cups fresh water and the gundruk soaking liquid (pour it in carefully leaving behind any sediment). The soaking liquid provides the sour fermented character.
9. Add potato and salt: Add the small diced potato and salt. Bring to a boil. Reduce to medium and cook 12 to 15 minutes until potato is fully cooked.
10. Serve: Ladle into bowls. Garnish with sliced spring onions. Serve with steamed rice or any bread.
11. Note: Gundruk is one of the most important traditional fermented foods of Nepal, Sikkim and Darjeeling — a technique for preserving leafy vegetables (mustard greens, radish leaves, cauliflower leaves) by wilting, fermenting at room temperature for 3 to 5 days and then sun-drying for long-term storage. It is the primary vegetable for the winter months in the Himalayan belt when fresh greens are unavailable. The soup made from rehydrated gundruk is sour, earthy and deeply warming.