Halve the pointed cabbage, remove the stalk, then halve the halves again lengthways and then cut across into strips approx. 1 cm wide. Cut the leek into medium-thick rings and the onion into thin rings, as well as the peppers. Cut the peppers into 0.5 to 1 cm wide strips, then divide them into thirds. Cut the tofu into small, narrow pieces.
Fry the tofu in a pan, possibly with a little oil, until it has turned golden yellow.
Heat 2-3 tablespoons of oil in another pan, add mustard seeds and fry for approx. 4 minutes. Then add the curry powder and continue frying for a few minutes. Then add the tofu from the other pan and mix everything. Add the onion rings and continue frying.
After approx. 4 minutes add the leeks and peppers, sauté briefly, add the cabbage strips and mix everything together. Then add the peppers, pour in a little water and season with salt. Put the lid on and let everything cook over medium heat for approx. 10 minutes. Add a little water if necessary (but no sauce should form).
When the cabbage has reached the desired consistency, remove the pan from the heat and season everything with freshly ground pepper, lemon juice and possibly a little salt.