Roast Salmon With Leeks Onions

The smell of roasted leeks sweetening in the oven always takes me straight back to a cold Tuesday when I needed dinner fast but refused to compromise on flavor. I had salmon thawing and a few lonely vegetables rolling around the crisper drawer. What started as improvisation turned into one of those meals where everyone went quiet at the table, too busy eating to talk. The parsley dressing was a last-minute idea, something bright to cut through the richness, and it pulled everything together so perfectly I've never made this dish without it since.

I made this for friends who claimed they didn't like cooked vegetables, and they scraped the pan clean. The leeks get caramelized and almost sweet, the onions soften into something mellow and rich, and the salmon stays tender with that crispy-edged skin. We ended up sitting around the table longer than usual, pouring more wine and talking until the candles burned down. It became the kind of meal I reach for when I want to impress without stress, when I want the food to feel generous and easy all at once.

Ingredients

• 4 salmon fillets (about 150 g each), skin-on: The skin protects the flesh and crisps up beautifully if you let it sit undisturbed on the hot pan, adding texture and keeping the salmon moist.
• 2 large leeks, trimmed and sliced into 1/2-inch rounds: Leeks turn jammy and sweet when roasted, and their mild onion flavor doesn't overpower the salmon but supports it perfectly.
• 1 large red onion, sliced into wedges: Red onion adds a pop of color and a slightly sharper sweetness that balances the mellowness of the leeks.
• 2 tbsp olive oil: Just enough to coat the vegetables and help them caramelize without making anything greasy.
• 1/2 tsp sea salt: Seasons the vegetables as they roast, drawing out moisture and concentrating their natural flavors.
• 1/4 tsp black pepper: A gentle background warmth that doesn't compete with the bright dressing to come.
• 1 lemon, sliced: Roasted lemon slices add a subtle bitterness and visual charm, and you can squeeze them over the fish at the table for extra brightness.
• 1 cup fresh flat-leaf parsley, finely chopped: The backbone of the dressing, parsley brings an herbal freshness that cuts through the richness of the salmon like nothing else.
• 1 small garlic clove, minced: Just one clove is enough to add sharpness without overwhelming the delicate parsley.
• 1/2 tsp Dijon mustard: The mustard emulsifies the dressing and adds a quiet tang that makes everything taste more alive.
• 1 tsp capers, drained and chopped: Capers bring brininess and little bursts of salty flavor that play beautifully with the salmon.
• 1/2 tsp lemon zest: The zest holds all the aromatic oils and gives the dressing a brightness that straight lemon juice alone can't achieve.
• 3 tbsp extra-virgin olive oil: Use your best olive oil here, it's the dressing's body and you'll taste every drop.
• 1 tbsp fresh lemon juice: Freshly squeezed juice is essential, bottled just won't have the same lively acidity.
• Salt and pepper, to taste: Adjust the dressing until it sings, a pinch more salt or pepper can transform it from good to unforgettable.

Instructions

Preheat the oven:

Set your oven to 400°F (200°C) and let it come fully to temperature while you prep. A properly heated oven ensures the vegetables start roasting immediately and the salmon cooks evenly.

Prepare the vegetables:

Spread the leeks and red onion across a large baking sheet in a single layer, drizzle with olive oil, and sprinkle with salt and pepper, tossing everything with your hands to coat. The single layer is key so they roast instead of steam, developing those sweet caramelized edges.

Start roasting:

Slide the baking sheet into the oven and roast the vegetables for 10 minutes. This head start softens them and begins the caramelization before the salmon joins the party.

Add the salmon:

Pull the pan out, nestle the salmon fillets skin-side down among the vegetables, and lay lemon slices over the top of each fillet. The vegetables cushion the salmon and the lemon infuses it with a gentle citrus perfume as everything finishes together.

Finish roasting:

Return the pan to the oven and roast for 12 to 15 minutes, until the salmon is just cooked through and flakes easily with a fork. Watch for that moment when the flesh turns opaque and tender, you don't want to overcook it or it will dry out.

Make the dressing:

While the salmon bakes, combine parsley, garlic, Dijon mustard, capers, lemon zest, olive oil, and lemon juice in a small bowl, stirring until everything is well mixed. Taste it and adjust the salt and pepper until it feels bright and balanced.

Serve:

Transfer the roasted salmon and vegetables to individual plates and spoon the parsley dressing generously over the top. Serve immediately while everything is hot and the dressing is fresh and vibrant.

Save

The first time I served this, my neighbor asked for the recipe before she even finished her plate. We stood in the kitchen while I scribbled it on the back of an envelope, and she made it that weekend and texted me a photo of her own version. That's the thing about this dish, it's simple enough that anyone can make it their own, but special enough that it feels like a gift every time you plate it up.

Serving Suggestions

I love serving this with roasted fingerling potatoes or a bowl of steamed jasmine rice to soak up the dressing. A crisp green salad on the side with a lemony vinaigrette echoes the brightness of the parsley and keeps the meal feeling light. If you want to go all out, a chilled white wine like Sauvignon Blanc or a dry Riesling makes the whole experience feel effortless and elegant.

Storage and Reheating

Leftovers keep well in an airtight container in the fridge for up to two days, though the salmon is best enjoyed fresh. If you do reheat, do it gently in a low oven to avoid drying out the fish, and save a little extra dressing to drizzle over the top so it tastes bright again. I've also flaked leftover salmon into a grain bowl with quinoa and arugula, and it was almost better the second day.

Variations and Swaps

If you can't find salmon or want to switch things up, trout or cod work beautifully with the same roasting time. You can swap the leeks for fennel if you want a hint of anise, or throw in some cherry tomatoes for bursts of sweetness. The parsley dressing is endlessly adaptable, add a pinch of red pepper flakes for heat, swap in cilantro or dill, or stir in a spoonful of Greek yogurt for creaminess.

• Try skin-on trout fillets for a more delicate flavor and the same crispy skin.
• Add halved cherry tomatoes in the last 5 minutes of roasting for juicy pops of sweetness.
• Stir a handful of chopped fresh dill into the dressing for a Scandinavian twist.

Save

This dish has become my go-to when I want to feel like I'm taking care of myself and the people I'm feeding without spending hours in the kitchen. It's proof that simple ingredients and a hot oven can create something truly memorable.

Recipe FAQs

→ Can I use a different type of fish?

Yes, trout or cod work well as substitutes. Adjust cooking time based on thickness—thinner fillets may need 10-12 minutes instead of 12-15.

→ How do I know when the salmon is done?

The salmon is ready when it flakes easily with a fork and reaches an internal temperature of 145°F. The flesh should be opaque and slightly pink in the center.

→ Can I prepare the parsley dressing ahead of time?

Absolutely. Make the dressing up to 24 hours in advance and store it covered in the refrigerator. Stir well before serving to reincorporate the ingredients.

→ What can I serve alongside this dish?

Roasted potatoes, steamed rice, quinoa, or crusty bread pair beautifully. A simple green salad also complements the rich flavors of the salmon and dressing.

→ Should I remove the salmon skin before serving?

That's a personal preference. The skin becomes slightly crispy when roasted and can be eaten or easily removed after cooking. Cooking with skin-on helps keep the fish moist.

→ How do I store leftovers?

Store leftover salmon and vegetables in an airtight container in the refrigerator for up to 2 days. Keep the parsley dressing separate and add fresh when reheating.