Mix the flour, eggs, salt and water together until smooth. Beat the spaetzle dough until it bubbles up.
Use the spaetzle slicer to spread the dough into the boiling water and wait briefly for it to bubble up / boil. Strain with a slotted spoon and rinse with cold water.
Salad:
Fry the onions with the bacon and oil and remove from the pan.
Fry the drained mushrooms with the leek in the bacon and season with salt and pepper. Deglaze with vinegar, cream and stock.
Mix all ingredients with the spaetzle and let it steep.