Peel onions and cut them into rings. Cut ham into bite-sized pieces. Grate cheese. Heat the fat. Fry 2 onions in it. Add the spaetzle, toss briefly. Fill into an ovenproof dish with ham and cheese.
Bake in the preheated oven (electric oven: 200 °C/ gas: level 3) for approx. 5 minutes. Wash and chop the parsley and sprinkle on top. For the salad, wash the tomatoes and cut them into slices. Rinse the corn and let it drip off.
Clean and wash lettuce and pluck into bite-sized pieces. For the marinade season vinegar with salt, pepper and sugar. Whip the oil into it. Mix tomatoes, mias, lettuce and the remaining onion rings with the marinade.
Serve the salad with the ham spaetzle.