Heat olive oil in a large skillet or pan over medium heat.

Add the chopped onion and sauté for 3-4 minutes until softened and translucent.

Stir in the julienned carrot and sliced zucchini. Cook for another 5-7 minutes, stirring occasionally, until vegetables start to tenderize.

Add the shredded cabbage to the pan. Cook for 3-5 minutes, stirring frequently, until it wilts down.

Gently place the fish fillets on top of the vegetables. Season with salt and pepper. If using, sprinkle dried dill over the fish and vegetables.

If using, pour in the canned diced tomatoes around the fish.

Cover the skillet and let it simmer for 8-12 minutes, or until the fish is cooked through and flakes easily with a fork.

Serve hot, optionally with cooked rice or quinoa on the side.