Grind the sesame seeds and desiccated coconut into a fine powder in a spice grinder.
Cut the peppers into thick slices.
Heat 1 T oil in a heavy pan. Fry the pepper strips on medium-high heat until charred at the edges and slightly wilted. Remove them and set them aside.
Heat 1 T oil in the same pan. Temper it with nigella seeds, mustard seeds and cumin.
Saute the onion and chillies until the onions are transluscent (but not browned).
Add the salt, red chilli powder and sesame-coconut powder and saute for a few minutes.
Add a cup of water and bring to a boil. Simmer for 5 minutes. Add the peppers, simmer for a couple of minutes more, then turn off the heat.
Stir in the lemon juice before serving.