Roast Salmon With Leeks Onions

Featured in: Warm Rustic Bake & Roast Recipes

This one-pan roasted salmon combines tender fish fillets with caramelized leeks and red onions, all finished with a bright parsley and caper dressing. The entire dish bakes together on a single sheet pan, making cleanup effortless. The parsley dressing adds a fresh, zesty contrast to the rich salmon, while the roasted vegetables provide natural sweetness. Perfect for busy weeknights when you want something healthy, flavorful, and satisfying without spending hours in the kitchen.

Updated on Fri, 30 Jan 2026 12:59:00 GMT
Roasted salmon fillets nestled with caramelized leeks and onions, finished with a bright parsley dressing on a rustic platter. Save
Roasted salmon fillets nestled with caramelized leeks and onions, finished with a bright parsley dressing on a rustic platter. | amberspill.com

The smell of roasted leeks still brings me back to a weeknight when I had twenty minutes before everyone got hungry and a single sheet pan to work with. I tossed vegetables on a tray, nestled salmon fillets among them, and slid everything into the oven. While it roasted, I whisked together a bright parsley dressing that turned the whole dish from simple to stunning. That night taught me that elegance doesn't require a sink full of dishes.

I first made this for a friend who claimed she didn't like salmon. She took one bite of the crispy-skinned fillet with the lemony, garlicky dressing and asked for the recipe before she finished her plate. The sweetness of the roasted onions and leeks, combined with that vibrant green sauce, won her over completely. It became my go-to whenever I wanted to prove that simple ingredients could create something memorable.

Ingredients

  • Salmon fillets (skin-on): The skin crisps beautifully in the oven and protects the delicate flesh, keeping it moist and tender throughout roasting.
  • Leeks: Their mild, sweet flavor mellows even more as they roast, adding a soft, almost buttery texture to the dish.
  • Red onion: Roasting transforms their sharpness into caramelized sweetness that balances the bright dressing.
  • Olive oil: Use a good quality oil for roasting the vegetables so they turn golden and flavorful, not dry.
  • Lemon slices: They infuse the salmon with citrus as it cooks and look beautiful on the plate.
  • Fresh flat-leaf parsley: The star of the dressing, it brings grassy brightness and a pop of color that makes the dish come alive.
  • Garlic: Minced finely, it adds a punchy backbone to the dressing without overpowering the parsley.
  • Dijon mustard: Just a hint gives the dressing body and a subtle tang that ties everything together.
  • Capers: Their briny sharpness cuts through the richness of the salmon and adds little bursts of flavor.
  • Lemon zest and juice: Fresh citrus brightens the dressing and keeps it lively and sharp.
  • Extra-virgin olive oil: The base of the dressing, it carries all the flavors and adds a silky finish.

Instructions

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Preheat and Prep:
Set your oven to 400°F (200°C) so it's hot and ready. This high heat will roast the vegetables quickly and give the salmon a beautifully cooked exterior.
Roast the Vegetables First:
Spread the leeks and red onion on a large baking sheet, drizzle with olive oil, and season with salt and pepper. Roast them for 10 minutes to give them a head start, so they caramelize and soften before the salmon joins them.
Add the Salmon:
Nestle the salmon fillets skin-side down among the vegetables and lay lemon slices over the top. Return the pan to the oven and roast for 12 to 15 minutes, until the salmon is just cooked through and flakes easily.
Make the Parsley Dressing:
While the salmon roasts, combine parsley, garlic, Dijon mustard, capers, lemon zest, olive oil, and lemon juice in a small bowl. Stir until everything is well mixed, then season with salt and pepper to taste.
Plate and Serve:
Transfer the salmon and vegetables to plates, then spoon the vibrant parsley dressing generously over the top. Serve immediately while everything is warm and fragrant.
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Keeps spices within easy reach while cooking, helping you season dishes quickly during everyday meal prep.
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Golden-baked salmon with tender leeks and red onion wedges, garnished with a vibrant green parsley dressing for a zesty finish. Save
Golden-baked salmon with tender leeks and red onion wedges, garnished with a vibrant green parsley dressing for a zesty finish. | amberspill.com

One evening, I served this with a simple arugula salad and a glass of cold white wine. My partner looked up after the first forkful and said it tasted like something we'd order at a seaside bistro. That's when I realized this recipe had become more than a weeknight shortcut, it was a little escape we could make any time we needed one.

Choosing Your Salmon

Look for fillets with firm, bright flesh and skin that still looks shiny. If you can, buy wild-caught salmon for deeper flavor, though farmed works beautifully too. I've learned to ask the fishmonger to leave the skin on, it protects the fish and crisps up in a way that adds texture and richness to every bite.

Making the Dressing Shine

The parsley dressing is where this dish gets its personality, so don't rush it. Chop the parsley finely so it blends smoothly with the other ingredients, and taste as you go. I sometimes add an extra squeeze of lemon or another teaspoon of capers if I'm feeling bold, the dressing should be bright, punchy, and alive.

Serving and Pairing Ideas

This dish is hearty enough to stand on its own, but I love pairing it with roasted baby potatoes or a scoop of steamed rice to soak up the dressing. A crisp green salad on the side adds contrast, and a chilled Sauvignon Blanc or sparkling water with lemon feels just right.

  • For extra heat, add a pinch of crushed red pepper flakes to the dressing.
  • Swap salmon for trout or cod if you want to try a different fish.
  • Leftovers reheat gently in a low oven and still taste fresh the next day.
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One-Pan Roast Salmon served alongside tender roasted vegetables, topped with a fresh lemony parsley sauce perfect for a quick dinner. Save
One-Pan Roast Salmon served alongside tender roasted vegetables, topped with a fresh lemony parsley sauce perfect for a quick dinner. | amberspill.com

This recipe has saved me on countless busy evenings and impressed guests more times than I can count. I hope it becomes one of those dishes you turn to when you want something delicious, healthy, and effortlessly beautiful.

Recipe FAQs

Can I use frozen salmon fillets?

Yes, but make sure to thaw them completely in the refrigerator overnight before cooking. Pat them dry with paper towels to ensure proper roasting and to prevent excess moisture on the baking sheet.

What other fish can I substitute for salmon?

Trout, arctic char, or cod work well as substitutes. Adjust cooking time slightly for thinner fillets like trout, checking for doneness around 10-12 minutes instead of 15.

How do I know when the salmon is perfectly cooked?

The salmon is done when it flakes easily with a fork and reaches an internal temperature of 145°F. The flesh should be opaque with a slightly translucent center for a moist, tender result.

Can I make the parsley dressing ahead of time?

Absolutely. Prepare the dressing up to 2 days in advance and store it in an airtight container in the refrigerator. Bring it to room temperature before serving for the best flavor and consistency.

What sides pair well with this dish?

Roasted baby potatoes, steamed rice, quinoa, or crusty bread complement the salmon beautifully. A simple green salad with lemon vinaigrette also makes a refreshing accompaniment.

Can I double this for a larger crowd?

Yes, use two large baking sheets to avoid overcrowding, which can cause steaming instead of roasting. Keep the vegetables and salmon in a single layer for even cooking and optimal caramelization.

Roast Salmon With Leeks Onions

Roasted salmon with leeks, onions, and a vibrant parsley dressing. Gluten-free and ready in 40 minutes.

Prep Time
15 minutes
Cook Time
25 minutes
Overall Time
40 minutes


Level Easy

Cuisine Modern European

Portions 4 Serving Size

Diet Preferences No Dairy, Gluten-Free, Low Carbohydrate

What You Need

Fish & Vegetables

01 4 salmon fillets (about 5.3 oz each), skin-on
02 2 large leeks, trimmed and sliced into 1/2-inch rounds
03 1 large red onion, sliced into wedges
04 2 tbsp olive oil
05 1/2 tsp sea salt
06 1/4 tsp black pepper
07 1 lemon, sliced

Parsley Dressing

01 1 cup fresh flat-leaf parsley, finely chopped
02 1 small garlic clove, minced
03 1/2 tsp Dijon mustard
04 1 tsp capers, drained and chopped
05 1/2 tsp lemon zest
06 3 tbsp extra-virgin olive oil
07 1 tbsp fresh lemon juice
08 Salt and pepper to taste

How To Make

Step 01

Preheat oven: Preheat the oven to 400°F.

Step 02

Prepare vegetables: Arrange leeks and red onion in a single layer on a large baking sheet. Drizzle with olive oil, sprinkle with salt and pepper, and toss to coat.

Step 03

Initial vegetable roasting: Roast the vegetables for 10 minutes.

Step 04

Add salmon: Remove the baking sheet from the oven. Nestle the salmon fillets skin-side down among the vegetables. Arrange lemon slices over the salmon.

Step 05

Complete roasting: Return to the oven and roast for 12 to 15 minutes, or until the salmon is just cooked through and vegetables are tender.

Step 06

Prepare parsley dressing: While the salmon bakes, combine parsley, garlic, Dijon mustard, capers, lemon zest, olive oil, and lemon juice in a small bowl. Stir well and season with salt and pepper to taste.

Step 07

Plate and serve: Transfer the roasted salmon and vegetables to plates. Spoon the parsley dressing generously over the salmon and serve immediately.

Equipment Needed

  • Large baking sheet
  • Sharp knife
  • Mixing bowls
  • Spoon or whisk

Allergy Details

Always check each item in your recipe for allergens. Reach out to a health expert with any concerns.
  • Contains fish (salmon)
  • Contains mustard

Nutrition Per Serving

Nutritional values are for reference and not a substitute for advice from a doctor.
  • Calories: 365
  • Fats: 23 grams
  • Carbohydrates: 10 grams
  • Proteins: 30 grams