Place potatoes and water in a microwave-safe dish. Microwave, covered, on high until potatoes are tender, 3-4 minutes; drain., Meanwhile, mix brown sugar, vinegar, mustard, thyme and pepper. In a large skillet, heat oil over medium-high heat; saute onion and kielbasa until onion is tender., Add potatoes; cook and stir until lightly browned, 3-5 minutes. Stir in brown sugar mixture; bring to a boil. Reduce heat; simmer, uncovered, 2 minutes, stirring occasionally. Stir in spinach until wilted. Stir in bacon.