For the curry lentils peel tomatoes, core and dice small. Peel the potatoes and cut into 2 cm pieces. Clean and cut celery into 1 cm pieces. Boil potatoes and celery separately in salted water until al dente, strain, rinse and drain.
Peel onion and garlic, cut into small pieces and fry in butter. Add thyme, cumin and coriander and cook briefly. STir in lentils and curry, douse with water, bring to the boil and simmer for about 10 minutes.
Pour in the cream, stir in potatoes and celery, boil up, possibly seasoning with salt and pepper.
Season catfish fillets with salt and pepper, cover one side with mustard and sprinkle with breadcrumbs. Heat oil in a nonstick skillet and place the fillets with the crumbs side down and fry them until crispy. Turm around fillets and fry ready. Serve with the lentil curry.