Mix beer, egg and flour to a smooth dough. Season with salt and cayenne pepper. Leave to swell for 30-40 minutes
Peel onions and cut them into 1/2 cm thick slices. Remove small, inner rings and use for other purposes. Place the onion rings in a bowl of cold water for about 1/2 hour
Finely grind or crush the crackers. Wash the tomatoes, dab dry and cut into slices of approx. 1 cm
Dab onion rings well dry. Heat the oil in a tall pot. First pull the onion rings through the batter and then turn them over in the cracker crumbs
Bake in hot oil in portions until golden brown. Drain on kitchen paper. Drizzle with a little vinegar
Prepare the tomato slices in the same way and drain well as well. Arrange everything and add the crème fraîche