Heat the oil, add the cumin and mustard seeds. Add the ginger, garlic clove then tumeric, green chili, onions, carrots and stir for a minute. Add the cabbage, tofu and potatoes and stir again. Add some water and cook covered for about 7-8 minutes until the vegetables become soft and the water is dried up. Add the salt and garam masala and stir well. Remove from heat and set aside.
For a variation on the filling you can add chopped bok choy, spinach, spring onion.
For the pastry :
Mix together all ingredients and knead to a ball.This needs a long knead until the dough is very soft, about 10-12 minutes. Wrap and rest for at least an hour.
To make the dumpling shape:
Take a knob of dough and roll out into small rounds about 10 cm in diameter. Spoon a little filling (heaped teaspoon) in the centre and moisten the edge with a little water. Press edges together overlapping the top slightly to form a pleat and continue all around to create a half moon shape with pleats all around the edge.
Steam for about 15 minutes until they are swollen and cooked through.