Add coriander leaves, coconut, green chilies, ginger&garlic paste, cumin seeds, turmeric, salt, and water to a blender. Grind to a smooth paste. Set aside.
Make the Muthiya
Mix besan, wheat flour, chopped methi leaves, turmeric, red chili powder, asafoetida, oil, and salt in a bowl. Add water gradually and knead into a firm dough.
Divide the dough into 12 to 15 small portions and shape into oval dumplings. Steam them in a steamer or idli maker for 12 to 15 minutes until cooked through. Let them cool slightly.
Cook the Undhiyu
Heat ghee in a heavy bottomed kadhai or deep pan over medium heat. Add mustard seeds and let them crackle. Add asafoetida and curry leaves.
Add the ground green masala paste and saute for 3 to 4 minutes until the raw smell disappears and oil begins to separate.
Start layering vegetables. Place raw banana and arbi pieces at the bottom as they take longest to cook. Add baby potatoes and purple yam next.
Layer surti papdi, brinjals, and green peas on top. Pour any remaining green masala over the vegetables. Sprinkle grated jaggery evenly.
Add 1/2 cup water around the edges of the pan. Do not stir. Cover with a tight lid and cook on low heat for 25 to 30 minutes.
After 25 minutes, gently place the steamed muthiya on top of the vegetables. Cover again and cook for another 12 to 15 minutes until all vegetables are tender.
Check if vegetables are cooked by inserting a knife into the bottom layer. If needed, cook for 5 more minutes with a few tablespoons of water.
Once done, very gently mix everything, taking care not to break the vegetables or muthiya. Adjust salt if needed.
Garnish with fresh coriander leaves and grated coconut. Serve hot.
Notes
Use a heavy bottomed kadhai or a wide pan with a tight fitting lid. This helps trap steam and cook vegetables evenly.If you cannot find surti papdi, substitute with green beans or valor papdi. The texture will be slightly different but still delicious.For quicker cooking, you can parboil arbi and raw banana for 5 minutes before adding to the curry. This reduces overall cooking time by 15 minutes.Make muthiya ahead and refrigerate for up to 2 days. Steam them fresh or use refrigerated ones directly in the recipe.Undhiyu tastes better the next day as flavors meld together. Reheat gently with a splash of water to prevent sticking.You can make this in a pressure cooker. After adding vegetables and water, pressure cook for 2 whistles on medium flame, then add muthiya and cook open for 10 minutes.Adjust the number of green chilies based on your spice tolerance. Gujarati Undhiyu is typically mildly spiced.