Roast Salmon With Leeks and Onions

My cousin showed up one Tuesday with a bag of leeks she didn't know what to do with, and I had salmon thawing on the counter. We stood in the kitchen staring at each other until I said, let's just throw it all on one pan and see what happens. The smell that filled the apartment 20 minutes later made us both laugh, because sometimes the best meals are the ones you don't plan. That night turned into a recipe I've made at least a dozen times since, always with the same ease and always with someone asking for the recipe.

I made this for my parents the first time they visited my new place, nervous they'd think I was still living on cereal and takeout. My dad, who usually drowns everything in hot sauce, ate the whole fillet without reaching for the bottle once. My mom asked if I'd been taking cooking classes, and I didn't have the heart to tell her it was a happy accident born from limited counter space and a tight schedule.

Ingredients

• Salmon fillets (skin-on): Skin-on keeps the fish from falling apart and crisps up beautifully if you let it sit undisturbed; buy the freshest you can find or use frozen and thaw it gently in the fridge overnight.
• Leeks: They get sweet and silky when roasted, but make sure you rinse them well between the layers because grit loves to hide in there and ruin a good bite.
• Red onion: The wedges caramelize just enough to add a hint of sweetness that balances the acidity of the lemon and dressing.
• Olive oil: Use a decent one for drizzling the vegetables; it doesn't need to be your fancy finishing oil, but it shouldn't taste like nothing either.
• Lemon (sliced): The slices roast right on top of the salmon, releasing their juice and leaving behind a slight bitterness that works surprisingly well.
• Fresh flat-leaf parsley: This is the star of the dressing, so don't skimp or swap it for dried; the freshness is what makes the whole dish come alive.
• Garlic (minced): One small clove is enough to add sharpness without overpowering the brightness of the parsley and lemon.
• Dijon mustard: It brings body and a subtle tang to the dressing, helping everything emulsify without adding heaviness.
• Capers: Chop them finely so you get bursts of briny flavor in every spoonful, not just one overwhelming bite.
• Lemon zest and juice: Zest first, then juice, and use the same lemon for both to save yourself from dirtying more cutting boards than necessary.

Instructions

Get the oven ready:

Preheat your oven to 400°F so it's fully heated by the time your vegetables are prepped. A hot oven is key to getting those edges caramelized without drying out the salmon.

Prep and roast the vegetables:

Spread the leeks and red onion on a large baking sheet, drizzle with olive oil, season with salt and pepper, and toss them around until everything glistens. Roast for 10 minutes so they get a head start and begin to soften before the salmon joins them.

Add the salmon:

Pull the sheet out, nestle the salmon fillets skin-side down right among the vegetables, and lay lemon slices over the top of each piece. Slide it back into the oven and roast for another 12 to 15 minutes, until the salmon flakes easily and the vegetables are tender with golden edges.

Make the parsley dressing:

While everything roasts, chop your parsley finely and combine it in a small bowl with minced garlic, Dijon mustard, chopped capers, lemon zest, olive oil, and lemon juice. Stir it all together and taste, adjusting salt and pepper until it feels bright and balanced.

Plate and serve:

Transfer the salmon and vegetables to plates, spoon the parsley dressing generously over the top, and serve immediately while everything is still warm. The contrast between the hot fish and the cool, zesty dressing is part of the magic.

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There was a night last spring when I made this for a friend going through a rough patch, and we ate it straight off the baking sheet with forks, sitting on my kitchen floor because the table was covered in her work papers. She said it was the first thing that tasted like something in weeks, and I realized that sometimes feeding people isn't about perfection, it's about showing up with something warm and real.

Choosing Your Salmon

I used to overthink salmon, standing in the fish section for way too long, but now I just look for firm flesh and a clean ocean smell, nothing fishy or off. Skin-on is my preference because it protects the fish and crisps up if you're lucky, but skinless works if that's what you find. If you're using frozen, let it thaw slowly in the fridge overnight rather than rushing it under water, because patience here really does pay off in texture.

Making It Your Own

This recipe is forgiving enough that you can swap the red onion for shallots, toss in some cherry tomatoes halfway through roasting, or use trout or cod instead of salmon. I've added a handful of olives to the vegetables before and it worked beautifully, and a friend of mine stirs fresh dill into the dressing instead of parsley when she makes it. The bones of the recipe stay the same, but the little changes keep it from ever feeling boring or repetitive.

Serving and Storing

I like serving this with something starchy to soak up the dressing, like roasted fingerling potatoes or a simple heap of steamed rice. Leftovers keep in the fridge for a day or two, though the salmon is best eaten fresh and the dressing loses some brightness if it sits too long. If you do have extra dressing, it's fantastic drizzled over roasted vegetables, grain bowls, or even scrambled eggs the next morning.

• Reheat leftovers gently in a low oven to avoid drying out the salmon.
• Double the dressing if you love sauce, it's the kind of thing you'll want extra of.
• Serve with a crisp white wine or sparkling water with lemon if you want the meal to feel a little more special.

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This dish has become one of those reliable friends in my kitchen, the kind I turn to when I want something nourishing without the fuss. I hope it finds a spot in your rotation too, because everyone deserves a meal that feels this easy and this good.

Recipe FAQs

→ Can I use frozen salmon fillets?

Yes, just ensure they are fully thawed and patted dry before roasting to achieve the best texture and even cooking.

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

The salmon should flake easily with a fork and reach an internal temperature of 145°F. It will appear opaque throughout with a slightly translucent center for medium doneness.

→ Can I prepare the parsley dressing in advance?

Absolutely. The dressing can be made up to 2 days ahead and stored in an airtight container in the refrigerator. Stir well before serving.

→ What other vegetables work well in this dish?

Try asparagus, cherry tomatoes, bell peppers, or fennel. Just adjust roasting times based on the vegetable's density and moisture content.

→ Can I make this without the skin on the salmon?

Yes, skinless fillets work fine. Reduce cooking time by 2-3 minutes and watch carefully to avoid overcooking.

→ How should I store leftovers?

Store cooled salmon and vegetables in an airtight container in the refrigerator for up to 2 days. Keep the dressing separate. Reheat gently in the oven at 300°F.