Easy Slow-Roasted Salmon with Pickled Onions and Fennel

Sometimes, the best recipes are the ones that require minimal effort but deliver maximum flavor. That’s exactly what you get with this Slow-Roasted Salmon with Pickled Onions and Fennel. It’s a dish that’s as simple as it is sophisticated, perfect for a weeknight dinner but impressive enough for your weekend dinner party.

Chef’s Tips:

  • Make Ahead: Prepare the pickled onions up to a week in advance, store them in a jar with a tight-fitting lid in your refrigerator, and let the vinegar do its work. The onions will soften slightly, becoming both tender and crisp while soaking up the brine’s tangy sweetness. This not only saves you prep time on the day of serving but also gives you a versatile condiment that can elevate salads, sandwiches, and more throughout the week.


  • Garnish: Those pickleed onions aren’t just for show. Adding them to the plate just before serving keeps their crunch and zing, making every bite a perfect balance of flavors.

Slow-Roasted Salmon with Pickled Onions and Fennel

5 from 2 votes
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Protein: Fish / Seafood, salmon
Cut: Salmon
Course: Lunch, Main Course
Prep Time: 1 day
Cook Time: 15 minutes
Total Time: 40 minutes
Servings: 6


  • 2 medium fennel bulbs thinly sliced (about 1½ cups sliced)
  • 1 small red onion thinly sliced
  • 2 tbsp yellow mustard seeds
  • 1 cup white vinegar
  • 2 tbsp honey
  • kosher salt & freshly ground pepper
  • 6 (4-7 oz.) ButcherBox Wild-Caught Alaskan Sockeye Salmon fillets
  • 2 tbsp extra-virgin olive oil
  • Fresh dill for garnish


  • In a medium glass container or jar, add the sliced fennel, red onion, and mustard seeds. In a medium saucepan, heat the vinegar, 1 cup of water, honey, and season generously with salt (about 1 tsp of kosher salt). Bring to a boil.
  • Pour the hot pickling liquid over the vegetables and set aside to cool. Once cooled, cover and transfer to the refrigerator overnight.
  • Preheat the oven to 325°F. Line a rimmed baking sheet with parchment paper. Pat the salmon dry, drizzle with the olive oil, sprinkle both sides with salt and pepper, and place on the baking sheet. Roast until cooked through, 10 to 15 mins, or longer, depending on the thickness of the fillets. Let cool to room temperature.
  • Arrange the salmon on a platter and top with tangles of pickled fennel and onions, spoonfuls of mustard seeds, and sprigs of fresh dill.
  • Tip: The salmon may be made in advance and refrigerated overnight.
  • Garnish with pickles just before serving.
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This Slow-Roasted Salmon with Pickled Onions and Fennel recipe is a testament to the beauty of simplicity in cooking. The mild heat gently coaxes the salmon to perfection, while the pickled veggies offer a bright contrast. It’s a dish that’s sure to become a new favorite in your dinner rotation. So, go ahead and treat yourself to this delightfully simple and utterly delicious meal. Your taste buds will thank you.