Shred the jackfruit with your fingers, pulling it apart into fine strands. Place the shredded jackfruit, cabbage, carrot and spring onion in a large bowl. Sprinkle with salt and use clean hands to massage everything together, for 2 minutes.
Allow to stand for 30 minutes (whilst you get on with making the dough). Once rested, squeeze as much water as you can out of the veggies. Return the squeezed vegetables to the bowl and stir in the coriander seeds, ginger, soy, oil and the salt and pepper.
Combine the flour and salt in a large bowl and gradually add the water. Use your hands to bring the ingredients together and form a firm dough. Place on a clean surface and knead for 5-10 minutes until smooth and elastic. Cover with a damp tea towel and rest for 10 minutes. Once rested, divide the dough into 30 equal balls, weighing about 15 grams each. Cover with a damp tea towel.
Roll out each ball of dough into a thin circle, approximately 12cm/5-inches in diameter. Dust with a sprinkle of cornflour and repeat for the remaining circles, stacking one on top of the other. Cover with a dry tea towel to prevent the momo wrappers from drying out.
Once ready to fill; hold one wrapper in the palm of your non-dominant hand. Fill the momo wrapper with about 2 teaspoons of the filling. Pack it as tightly as you can into the centre of the wrapper. Use your finger to wet the outer edges of the wrapper. Use the thumb and index finger of your dominant hand to begin pleating the edges of the wrapper around the filling, creating a fluted edge as you lightly pinch the seams together. Continue to pleat the edges in this way all the way around the filling. Gently pinch and twist the wrappers in the centre to cover the filling and close the momo completely. Repeat for the remaining momos.
As you work, put the finished momos on a baking tray or plate lined with greaseproof paper that’s been lightly dusted with cornflour. When done, loosely cover with a dry tea towel to prevent them drying out.
To cook the momos, fill a large pot or wok halfway with water and bring to a boil over a high heat. Place a smaller-sized bamboo steamer or metal over the water, ensuring the water does not touch the base of the steamer.
Line a bamboo steamer with greaseproof paper with holes punched in to allow the steam to penetrate, or alternatively line with a cabbage leaf. If using a metal steamer, lightly grease the perforated basket with oil. Arrange the momos in a single layer inside the steamer, ensuring you leave some space between each one so they do not touch. They will not inflate significantly but the gap will allow for even cooking and ensure they don’t stick together. Cover and steam over a medium-high heat for 12 minutes. Remove with tongs. Repeat the steaming process for any remaining momos, ensuring there is enough water in the pot before cooking more batches. The number of momos you can steam at once will depend on the side of your steamer. We used a 25cm round (10-inch) two-tiered bamboo steamer and cooked 10 momos per batch.
Heat the oil in a medium sized non-stick pan. Add the garlic, chilli and sesame seeds and fry for 20-25 seconds. Next, add the tomatoes and salt and cook over a medium heat for 5 minutes, stirring often. Remove from the heat and allow to cool. Blend to a smooth paste. Sieve the chutney into a bowl to remove any tomato skins and seeds. Cover and refrigerate until ready to serve.