Rinse the poha under running water for a few seconds until softened. Set aside to drain. Gently fluff it up with a fork.
Heat oil in a pan over medium heat. Add mustard seeds, cumin seeds, and asafoetida. Let them sputter for 30 seconds. Then, add the diced onion and sauté until lightly golden.(Optional) Add the peanuts with the onions only if unroasted.
Add green chili and curry leaves and fry until crisp.
Add cubed potatoes and salt. Cover and cook, stirring occasionally, until tender and lightly browned.
Add the turmeric, Kashmiri chili powder, and garam masala with the green peas. Sauté for a minute, then add the poha and mix to cover with the spices.
Stir in peas along with the turmeric, Kashmiri chili powder, and garam masala. Cook for a minute, then add in the softened poha and gently mix to coat with the spices.
Add the diced tomatoes, mix, then cover and cook for 2-3 minutes so the tomatoes soften and release moisture.
Turn off the heat. Stir in the peanuts and chaat masala.
Garnish with cilantro and serve with lemon juice or green chutney.