Cook the spaetzle following the package directions, adding the sliced carrots for the last 10 minutes of cooking.

Meanwhile, slice the pork tenderloin in half lengthwise; then slice crosswise into thin slices, 1/4 to 1/2-inch thick. Place pork slices in plastic food-storage bag with the flour, 1/4 teaspoon pepper and 1/4 teaspoon salt; seal; shake to coat the pork slices evenly.

Heat the butter in a large saucepan over medium-high heat. Working in batches to avoid crowding the skillet if necessary, add the pork slices. Cook, turning over, until no longer pink, about 5 minutes. Add the frozen green beans, breaking them apart, and onions; cook, stirring, for 4 minutes.

Meanwhile, whisk together sour cream, mustard, milk, dill, remaining 1/2 teaspoon pepper and remaining 1/4 teaspoon salt in a bowl. Add to pork mixture in skillet, stirring constantly. Reduce heat to medium; cook, uncovered, 5 minutes or until vegetables are tender and sauce is thick and creamy.

Drain spaetzle-carrot mixture. Arrange on platter. Top with pork-vegetable mixture. Serve immediately.