Also known as Chinese cabbage, napa cabbage is delicious on top of this salmon that is cooked in a skillet.
In a large, deep skillet with a lid, cook bacon over medium until crisp, turning occasionally, 5 to 8 minutes. With a slotted spoon, transfer to a paper-towel-lined plate; set aside. Pour off all but 2 tablespoons fat from skillet.
Raise heat to medium-high. Season salmon with salt and pepper. Cook in skillet until browned, 1 to 2 minutes per side (salmon will finish cooking in step 4). Transfer to a plate and reserve.
Add as much cabbage to skillet as will fit; add vinegar. Cover skillet, and cook over medium-high, tossing occasionally. Add remaining cabbage as there is room, until tender, 10 to 12 minutes; season with salt and pepper.
Stir in bacon, and place salmon on top. Cover skillet; cook until salmon is opaque throughout, 3 to 5 minutes. Transfer cabbage and bacon onto four plates, placing salmon on top.