Make a "cream" by blending the cashews or pistachios (or pumpkin seeds) into a smooth paste with ½ cup water. Set aside.
Heat the oil in a wide saucepan or skillet or, preferably, a wok. Add cumin seeds and let them darken a bit and become fragrant, about 30 seconds.
Add the finely chopped onion with a bit of salt and saute over medium heat until the onions brown. You don't want to caramelize them thoroughly but you should have good color on the onions so they just melt into the sauce.
Add the julienned ginger and crushed garlic and the minced green chili pepper, if using, and saute for a few seconds.
Add the two finely chopped tomatoes followed by the tomato paste. Mix.
Stir in the powdered spices: turmeric, cayenne and ground coriander. Add the crushed kasoori methi. Mix everything thoroughly and cook over medium heat for about 10 minutes, stirring frequently, until the tomatoes are thoroughly broken down and have formed almost a paste along with the onions. If needed add a splash of water to keep the tomatoes and onions from burning or sticking to the bottom of the pot.
Add to the cashew/pistachio/pumpkin-seed paste to the tomato-onion sauce in the wok and mix well. If you want a saucier jalfrezi, you can add about ½ cup water to the wok at this time and mix.
Add the carrots, cut into batons, to the pot. Mix, cover, and let the carrots cook five minutes. Stir once or twice to make sure nothing's sticking.
Add the remaining veggies to the pot--bell peppers, cabbage, carrots and zucchini. Mix well and let the veggies cook over medium or medium-high heat, stirring them frequently, for about three to five minutes or until they are tender enough but still have a good bite.
Add a sliced onion and a sliced tomato to the pot and stir in. Add garam masala and salt. You can also add some ground black pepper, if you want a bit more spice. Stir in the vinegar. Mix well and turn off the heat.
Garnish with cilantro before serving.