Rinse the channa dal and add to a pot with 2 cups of water. Bring to a boil and cook for about 10 minutes.

Add the potato chunks and salt to the dal. Cook until potatoes are tender enough to mash.

Mash the potatoes and dal together to form a smooth base.

Add the cauliflower, carrots, and green peas to the mashed mixture. Cook for approximately 15 minutes until all vegetables are tender, adding water as needed to maintain moisture.

Meanwhile, heat oil in a skillet over medium heat. Add mustard seeds and wait for them to pop.

Add the whole red chilies and chopped onions to the skillet. Sauté until onions become translucent and slightly golden.

Transfer the cooked vegetable mixture to the skillet with the spiced onions. Cook together for about 5 minutes, ensuring the texture is moist but not soupy.

Stir in the red chili powder and pao bhaji masala. Adjust seasoning to taste.

For the bread rolls, heat a separate skillet with a little oil. Split the rolls and toast them until golden-brown on the cut sides.

To serve, place a generous portion of the vegetable mixture (bhaji) on a plate alongside a toasted roll (pao). Top the bhaji with a slice of fresh tomato if desired.