German Lentils with Spaetzle (Schwäbische Linsen mit Spätzle)

Name: German Lentils with Spaetzle (Schwäbische Linsen mit Spätzle)
Prep time: 10 min
Cook time: 50 min
Total time: 1 h
Cuisine: European, German
Ingredients: 5 slices thick cut bacon, diced; 1 large yellow onion, finely diced; 1 tablespoon butter; 1 carrot, finely diced; 1 leek, finely chopped, thoroughly rinsed and drained; 1 pound dried brown lentils, rinsed and drained (no need to soak); 7 cups beef broth; 1 bay leaf; 1 teaspoon salt; ¼ teaspoon freshly ground black pepper; 1 teaspoon white sugar; ¼ cup white vinegar; 3 tablespoons chopped fresh parsley; Homemade German Spätzle or store-bought