Prepare the Vegetables:

Wash the cauliflower florets and potato cubes thoroughly. Drain any excess water.

Cook the Vegetables:

Heat oil in a large pan or wok over medium heat. Add cumin seeds and let them splutter.
Add the onions and sauté until they turn golden brown.
Stir in the ginger-garlic paste and green chilies, cooking until the raw smell disappears.
Add the turmeric, coriander, cumin, and red chili powders. Mix well.
Add the potatoes, mixing well to coat them with the spices. Cook for 5-7 minutes, stirring occasionally.
Introduce the cauliflower florets and salt. Stir well, ensuring the florets are coated with the spice mixture. If using tomatoes, add them now.
Reduce the heat to low. Cover the pan and let the vegetables cook, stirring occasionally, until they are tender but not mushy, about 15-20 minutes. If the mixture seems too dry, you can add a splash of water to prevent sticking.

Final Touches:

Once the vegetables are cooked, sprinkle garam masala over the top and mix gently.
Adjust the seasoning, adding more salt or chili powder if needed.

Serve:

Garnish with fresh coriander leaves. Serve hot with roti, naan, or steamed rice.