Cooking salmon from frozen is one of the most useful techniques a home cook can add to their toolkit. It eliminates planning stress, reduces waste, and—when you use the cast‑iron‑to‑oven method—delivers reliably moist flesh with an appealing, blistered skin. This friendly, step‑by‑step tutorial walks you through ingredients, prep time, the exact cooking method, serving size guidance, and easy dietary modifications.

Why this method works

Searing frozen salmon in a hot cast‑iron skillet locks the skin and some surface protein, then finishing the fish in a moderately hot oven cooks the center gently. The approach balances high-heat crisping with steady, even internal cooking—especially useful for skin‑on portions straight from the freezer.

Ingredients & servings

Serves 2 (double or triple the recipe as needed; see “Scaling” below)

  • 2 skin‑on salmon fillets (6–7 oz / 170–200 g each), frozen solid
  • 1–1½ tsp kosher salt (divided)
  • ½ tsp freshly ground black pepper
  • 1 tbsp neutral oil with high smoke point (grapeseed, avocado, or vegetable)
  • 2 tbsp unsalted butter (optional, for finishing)
  • 1 lemon, cut into wedges
  • 2 sprigs fresh thyme or 4–6 fresh sage leaves (optional)

Prep time and total time

  • Active prep time: 5 minutes
  • Cook time: 18–22 minutes (depends on fillet thickness)
  • Total time: 23–27 minutes

Tools

  • 12‑inch (30 cm) cast‑iron skillet or heavy ovenproof skillet
  • Instant‑read thermometer
  • Tongs or fish spatula
  • Oven set to 400°F (205°C)

Step-by-step: Cast‑Iron to Oven

  1. Preheat the oven. Set the oven to 400°F (205°C). Place a rack in the middle position.
  2. Score and salt the skin. Run the tip of a paring knife lightly through the skin crosswise two or three times to prevent curling. Sprinkle ¾ tsp salt evenly across the skin side of each frozen fillet.
  3. Pat and season the flesh. If there’s frost, quickly blot excess ice with a paper towel. Turn fillets skin‑side down and season the flesh with the remaining ¼–½ tsp salt and the pepper.
  4. Heat the skillet and oil. Place the skillet on medium‑high heat for 2 minutes. Add the oil and heat until shimmering but not smoking (about 30–45 seconds).
  5. Sear skin side down. Gently place each fillet skin‑side down in the hot skillet. Press lightly with a spatula for the first 10 seconds to ensure full contact. Sear without moving for 3–4 minutes, until the skin is deep golden and releases easily.
  6. Flip and transfer to oven. Flip each fillet so skin is up. Add butter and herbs (if using) to the pan, spoon a little melted butter over the tops, then immediately transfer the skillet to the preheated oven.
  7. Finish in the oven. Roast 6–12 minutes, depending on thickness: thinner fillets (3⁄4 inch / 2 cm) will need ~6–8 minutes; thicker pieces (1–1¼ inch / 2.5–3 cm) 9–12 minutes. Target internal temperature: 120–125°F (49–52°C) for medium-rare to medium; 130°F (54°C) if you prefer fully opaque.
  8. Rest briefly and serve. Remove skillet, transfer fillets to a plate, tent loosely with foil for 2–3 minutes. Serve with lemon wedges and any pan juices spooned over the fish.

Key technique tips

  • Do not thaw fillets completely under running water—work from frozen to preserve texture and reduce bacterial risk.
  • If there's a lot of ice between skin and flesh, pat dry as best you can; excess moisture prevents a crisp sear.
  • Use an instant‑read thermometer to avoid overcooking—salmon continues to cook a bit while resting.
  • For very large fillets, sear for an extra minute and add 2–3 minutes in the oven.

Dietary modifications

  • Low‑sodium: Reduce added salt by half; finish with a squeeze of lemon and fresh herbs for flavor.
  • Keto/Paleo: This recipe is naturally compatible—use avocado oil and skip the sugar-containing marinades.
  • Gluten‑free: Naturally gluten‑free; watch cross‑contamination if using shared cookware.
  • Vegetarian swap: Try the same method with thick slices of firm, frozen halloumi or marinated, firm tofu (increase oven time by 3–5 minutes for tofu).

Serving size, sides and make‑ahead

One 6–7 oz fillet is a standard serving size for an adult main course. Serve with simple sides that complement the crispy skin: a quick mustard‑dill vinaigrette, sautéed green beans, roasted fingerling potatoes, or a warm barley salad. Leftover cooked salmon keeps 2 days refrigerated—use flaked in salads, grain bowls, or a warm pasta.

Alternate cooking methods

  • Oven‑only: Preheat oven to 425°F (220°C) and roast frozen skin‑on fillets on a rimmed baking sheet for 12–18 minutes—skin won’t be as blistered as cast‑iron sear.
  • Air fryer: Preheat to 400°F (205°C); place frozen fillets skin‑side up and cook 9–12 minutes. Flip and cook 2 more minutes for crispier skin.

Final encouragement

Cooking fish straight from the freezer takes the guesswork out of dinner and often gives better results than partially thawing. With a hot skillet, an oven finish, and an instant‑read thermometer, you can get flaky, moist salmon and a skin that snaps with every bite—any night of the week. Try it this week with seasonal greens or a simple grain salad and enjoy how fast, forgiving, and delicious frozen salmon can be.