Roast Salmon With Leeks Onions

My neighbor knocked on my door holding a bag of leeks from her garden, insisting I take them before they bolted. I had salmon thawing and no plan, so I tossed everything onto one pan with sliced onions and lemon. The smell that filled my kitchen that evening—sweet roasted alliums mingling with the richness of roasting fish—made me realize sometimes the best meals come from happy accidents. That bright parsley dressing I whisked together at the last second became the thing I now crave every time I make this dish.

I started making this on Sunday nights when I wanted something nourishing but couldnt face a pile of dishes. My kids, who usually turn their noses up at anything green, started fighting over the roasted leeks. One evening my daughter announced she wanted to bring leftovers for lunch, which felt like a quiet victory I didnt see coming.

Ingredients

• Salmon fillets (skin-on): Skin-on fillets stay moist and hold together beautifully during roasting, plus the skin crisps up just enough to add texture.
• Leeks: These mild, sweet onions become buttery and tender when roasted, offering a gentler flavor than regular onions.
• Red onion: Wedges of red onion caramelize at the edges and add a slight sharpness that balances the richness of the fish.
• Olive oil: Use a good quality oil for roasting—it coats the vegetables evenly and helps them brown without burning.
• Sea salt and black pepper: Simple seasoning lets the natural flavors shine without crowding the palate.
• Lemon slices: They roast right on top of the salmon, releasing their oils and adding subtle citrus notes throughout.
• Fresh flat-leaf parsley: The backbone of the dressing, parsley adds herbal brightness and a grassy freshness that cuts through the richness.
• Garlic clove: Just one small clove minced fine gives the dressing a gentle bite without overpowering.
• Dijon mustard: A half teaspoon adds creaminess and tang, helping the dressing cling to the salmon.
• Capers: Chopped capers bring briny pops of flavor that wake up every bite.
• Lemon zest and juice: Fresh zest has oils that dried lemon cant match, and the juice brightens everything it touches.
• Extra-virgin olive oil: For the dressing, use your best bottle—this is where quality really shows.

Instructions

Get the oven ready:

Preheat your oven to 400°F (200°C) so its fully heated when the vegetables go in. A properly hot oven ensures even roasting and caramelization.

Prep the vegetables:

Spread the sliced leeks and red onion wedges across a large baking sheet in a single layer. Drizzle with olive oil, season with salt and pepper, then toss with your hands to coat every piece evenly.

Start roasting the vegetables:

Slide the sheet into the oven and roast for 10 minutes. This head start gives the vegetables time to soften and begin browning before the salmon joins them.

Add the salmon:

Pull the sheet out and nestle the salmon fillets skin-side down among the vegetables, tucking lemon slices on top of each piece. Return to the oven and roast for 12 to 15 minutes until the salmon flakes easily and the vegetables are tender.

Make the parsley dressing:

While everything roasts, combine chopped parsley, minced garlic, Dijon mustard, capers, lemon zest, olive oil, and lemon juice in a small bowl. Stir until well mixed, then taste and adjust salt and pepper as needed.

Plate and serve:

Transfer the roasted salmon and vegetables to plates. Spoon the vibrant parsley dressing generously over each fillet and serve right away while everything is hot.

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The first time I served this to friends, someone asked if Id taken a cooking class. I laughed and said no, just a neighbor with too many leeks. That moment reminded me that impressive food doesnt need to be complicated—it just needs to taste like you care.

Choosing Your Salmon

I used to grab whatever salmon was on sale, but Ive learned that thicker fillets hold up better to roasting and stay moister. Look for pieces that are uniform in thickness so they cook evenly. If you can only find skinless fillets, thats fine—just reduce the roasting time by a minute or two and keep a closer eye on them.

Making It Your Own

This recipe is forgiving and loves improvisation. Ive swapped the red onion for shallots when thats what I had, and Ive used trout and cod with equal success. If parsley isnt your thing, try cilantro or a mix of herbs. A pinch of red pepper flakes in the dressing adds a gentle heat that some people in my house now insist on every time.

Serving and Storing

I like this with roasted potatoes or a simple bowl of steamed rice to soak up the dressing. Leftovers keep 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 it out.

• Serve with crusty bread to mop up any extra dressing on the plate.
• A crisp green salad on the side balances the richness beautifully.
• Double the dressing recipe if you love it as much as I do—it keeps for three days and works on grilled chicken too.

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This dish has become my go-to when I want something that feels like a gift to myself without the fuss. I hope it brings you the same kind of easy joy it brought to my table.

Recipe FAQs

→ Can I use frozen salmon fillets for this dish?

Yes, but make sure to fully thaw the salmon fillets before cooking. Pat them dry with paper towels to remove excess moisture for better roasting results.

→ What can I substitute for leeks?

You can use sliced fennel bulb, shallots, or additional onions. Each will bring a slightly different flavor profile but work well with the salmon.

→ How do I know when the salmon is properly cooked?

The salmon is done when it flakes easily with a fork and reaches an internal temperature of 145°F (63°C). It should be opaque throughout but still moist.

→ Can I make the parsley dressing ahead of time?

Absolutely. Prepare the dressing up to 24 hours in advance and refrigerate in an airtight container. Stir well before serving as the oil may separate.

→ What other fish works well with this preparation?

Trout, cod, halibut, or sea bass are excellent alternatives. Adjust cooking time based on thickness—thinner fillets may need 2-3 minutes less.

→ How should I store leftovers?

Store cooked salmon and vegetables separately from the dressing in airtight containers in the refrigerator for up to 2 days. Reheat gently to avoid drying out the fish.