Heat mustard oil and sauté bhindi on medium-low flame for 2 minutes. Add turmeric and cook for another 4–5 minutes. Remove and keep aside.
In another pan, heat oil. Add mustard seeds, cumin, coriander seeds, fennel, and asafoetida. Add potatoes and cook till 70% done and slightly crisp. Add ginger and green chillies. Sauté for 2 minutes.
Add bhindi back, mix, cover, and cook for 3–4 minutes.
Add chilli powder, garam masala, salt, and roasted besan. Mix well. Cover and cook for 4–5 minutes. Finish with lime juice.