Step 1

Halve 12 to 16 ounces kielbasa sausage lengthwise, then cut crosswise into 1/2-inch-wide pieces. Core and chop 1/2 head green cabbage into rough 1-inch pieces (about 8 cups).

Step 2

Melt 2 tablespoons unsalted butter in a large cast iron or regular skillet over medium-high heat. Add 1/4 teaspoon caraway seeds and a pinch red pepper flakes, and cook until fragrant, about 30 seconds. Add the kielbasa and cook until browned, 6 to 8 minutes.

Step 3

Add the cabbage, 1/4 teaspoon kosher salt, and 1/4 teaspoon black pepper, and cook, stirring occasionally and scraping the bottom of the pan to release any browned bits, until tender and lightly browned, 8 to 10 minutes. Add 1 tablespoon whole-grain mustard and 1 tablespoon apple cider vinegar and toss to combine.