Whisk together besan, yogurt, red chili powder, turmeric, coriander powder, and water in a large bowl until smooth. Set aside.
For pakoras, combine besan, sliced onion, green chili, cilantro, turmeric, red chili powder, coriander seeds, ajwain, and salt in a bowl.
Add yogurt and water to pakora mixture, mix well. Add baking soda and stir gently.
Heat oil for deep frying. Drop spoonfuls of pakora batter into hot oil and fry until golden brown and crispy. Remove and drain on paper towels.
Heat mustard oil in a heavy-bottomed pan. Add methi seeds, cumin seeds, and hing. Let them splutter.
Add sliced onions and sauté until golden brown.
Add chopped green chili, ginger, and garlic. Cook for 2-3 minutes until fragrant.
Pour the prepared kadhi mixture into the pan while stirring continuously to prevent lumps.
Bring to a boil, then reduce heat and simmer for 20-25 minutes until kadhi thickens.
Add salt to taste and gently fold in the fried pakoras.
Simmer for another 5-7 minutes. Garnish with chopped cilantro before serving.