Cook the whole unripe bananas (with skin) in a pressure cooker for up to three whistles on high heat.
Peel the bananas and mash the flesh. Add the ginger-garlic paste, chopped green chilli, coriander leaves, mint leaves, mustard powder, garam masala, jeera powder, and kala namak.
Mix well to form a smooth and pliable mixture.
Divide the mixture into six equal parts and shape into medium-sized cutlets.
Heat a skillet and lightly grease with some oil. Place the cutlets on the hot skillet and cook for 2-3 minutes on medium-high heat.
Flip the cutlets and cook on the other side for 2-3 minutes. Repeat the process until both sides are golden brown. Serve hot with ketchup or chutney.