Soak the raw cashews in warm water for 15 minutes, then blend with the coconut milk until perfectly smooth to create the creamy base.
Heat the vegetable oil in a large heavy-bottomed pan over medium heat. Add the finely chopped onions and saute for 5 to 7 minutes until golden brown.
Stir in the ginger-garlic paste and chopped tomatoes. Cook until the tomatoes break down completely and the oil begins to separate from the mixture.
Add the turmeric powder, coriander powder, and garam masala. Stir continuously for 1 minute to lightly toast the spices and release their aroma.
Add the diced potatoes, carrots, green peas, water, and salt. Bring the mixture to a gentle boil, then cover and simmer for 15 minutes until all vegetables are fork-tender.
Reduce the heat to low. Stir in the blended cashew-coconut sauce and simmer for an additional 3 to 5 minutes, ensuring it does not come to a hard boil.
Remove from heat, garnish with fresh chopped cilantro, and serve hot alongside steamed basmati rice or warm naan bread.