For the sauce, peel and chop the onion. Wash the chillies, dab dry and cut in half lengthwise. Remove seeds and chop. Fry onion and chillies in hot oil. Add tomato pieces and let it boil down in an open pot for 10-15 minutes.
Season sauce with salt and pepper and let it cool down. Wash the fish, dab dry and cut into cubes. Peel potatoes, cut them into thin slices and fry them crispy in plenty of hot oil. Whisk egg and milk. Mix flour and breadcrumbs. Season fish with salt and pepper. First whisk the egg, then turn it in the flour and breadcrumbs mixture. Fry in hot oil for about 5 minutes. Drain fish and potatoes on kitchen paper.
Mix flour and breadcrumbs. Season fish with salt and pepper. First whisk the egg, then turn it in the flour and breadcrumbs mixture. Fry in hot oil for about 5 minutes. Drain fish and potatoes on kitchen paper. Season potatoes with salt