Wash the potatoes thoroughly and cut them into halves or quarters.

Place the potatoes in a pot of salted boiling water and cook for 8–10 minutes until fork-tender. Drain and set aside.

Pat the cod fillets dry with paper towels and season each fillet with salt, pepper, lemon juice, and lemon zest. Let them marinate while preparing the pan.

Heat 2 tablespoons of olive oil and 1 tablespoon of butter in a large skillet over medium-high heat.

Place the cod fillets in the pan and sear for 3–4 minutes per side until golden and cooked through. Remove from the pan and set aside on a warm plate.

In the same skillet, reduce heat to medium. Add olive oil, garlic, and shallots. Cook for 2–3 minutes until fragrant and translucent.

Stir in chopped rosemary and sauté for another minute.

Pour in the halal-certified broth and bring to a gentle simmer.

Stir in the heavy cream and Dijon mustard (if using). Simmer for 6–8 minutes, stirring occasionally, until the sauce thickens slightly.

Return the boiled potatoes to the skillet, gently tossing them in the cream sauce. Cook for an additional 3–4 minutes.

Carefully place the seared cod fillets back into the skillet, spooning sauce over each piece. Let everything simmer together for another 2–3 minutes on low heat.

Garnish with freshly chopped parsley or chives, if desired, and serve hot, either plated individually or family-style with crusty bread or a side salad.