Season the cod fillets with salt, pepper, and dried thyme.
Heat the olive oil in a large skillet over medium heat.
Add the sliced onion and minced garlic to the skillet and cook until softened.
Add the thinly sliced cabbage to the skillet and cook until wilted.
Move the cabbage mixture to the sides of the skillet and place the cod fillets in the center.
Cook the cod fillets for about 5 minutes on each side, or until cooked through.
Serve the cod and cabbage sauté hot.