Microwave potatoes on high 4 minutes or until tender.

In a large skillet, saute kielbasa and onion in oil.

Add potatoes. Saute 4-5 minutes or until kielbasa and potatoes are browned.

Combine the brown sugar, vinegar, mustard, thyme and pepper; stir into skillet. Bring to a boil. Reduce heat; simmer, uncovered, for 2-3 minutes or until heated through. Add spinach; cook and stir until spinach is wilted.