Roast the Peas: Heat a heavy-bottomed pan or tawa (iron griddle is best). Dry roast the fresh green peas until they get light brown spots. Remove and set aside.
Steam the Veggies: In the same pan, add a teaspoon of oil. Add the chopped brinjals and potatoes. Sprinkle a little salt, mix well, and cover with a lid. Cook on medium heat for 10–15 minutes until they are soft. (The salt helps them release water and cook in their own steam!). Remove them once cooked.
Prepare the Green Paste (Thecha): While the veggies are cooking, take your roasted green chillies, roasted garlic cloves, and fresh coriander. Crush them in a mortar and pestle or give them a quick pulse in a mixer to make a coarse paste.
Make the Tempering: Add a little more oil to the hot pan. Add cumin seeds and let them splutter. Add a pinch of hing and the chopped onions. Sauté until the onions turn translucent or light pink.
Add Greens and Spices: Add the turmeric powder and the prepared green chilli-garlic paste. Sauté for a minute. Then, add the chopped fenugreek (methi) leaves and cook until they wilt slightly.
Combine Everything: Add the roasted peas back into the pan. Add the cooked brinjal and potato mixture. You can mash the veggies slightly with a spatula if you prefer a softer texture or keep them chunky.
Final Touch: Add the coarse peanut powder and adjust salt if needed. Mix everything gently. Cover and cook on low heat (steam) for another 2–3 minutes to let the flavours blend.
Serve: Turn off the heat. Your spicy, rustic Vangi Batata Bhaji is ready!