Microwave the potatoes with salt and pepper until fork-tender, about 6-8 minutes, stirring halfway through.
Heat oil in a large skillet over medium-high heat. Add onions and cook until softened, about 3 minutes. Add garlic and kielbasa; cook, stirring, for 3 minutes.
Add the cooked potatoes to the skillet. Toss to coat and cook for 2-3 minutes, stirring occasionally, until lightly browned.
Add cabbage and water, and cook until the cabbage is wilted, about 2 minutes.