Drain and rinse the banana blossoms. Combine the ingredients for the marinade (water, salt, apple cider vinegar, lemon juice, and small pieces of nori) and cover the banana blossoms. Let them soak in the marinade for at least 20 minutes, meanwhile, we're making the curry.
In a pan over medium heat with oil, cook the onion until soft. Then add the garam masala and ginger and let it cook for another minute. Then turn the heat down and add the tomato purée and cashew cream. Give it a stir, add salt and more to taste and set it aside once warm.
In a bowl for the flour coating, combine the flour, salt, and curry powder.
Bring a grill pan to high heat, add a bit of oil. Dip the marinated banana blossoms into the flour on all sides, then add them to the grill pan. Once they have nice grill marks on one side, flip them around so that they will get those nice marks on all the sides.
Reheat the curry if it has cooled down by now, and add it to plates. Lay the crispy banana blossom fish on top of the curry. It's best served with basmati rice and naan.
*If your banana blossoms are smaller, you can use these, of course, just make more per serving!