Cook onion in hot butter in a covered large skillet over medium-low heat for 13 to 15 minutes or until onion is tender. Uncover; add sweet pepper, brown sugar, and vinegar. Cook and stir over medium-high heat for 4 to 5 minutes or until onion is golden. Stir in the broth, half-and-half, dill, and black pepper. Boil gently until mixture is thickened.
Meanwhile, cook spaetzle according to package directions, adding Brussels sprouts to the water with the spaetzle. Drain; return pasta and sprouts to pan.
Add caramelized onion mixture and pork to saucepan. Cook and stir over low heat until spaetzle are well coated and mixture is heated through. Makes 4 servings.