White Fish with Caramelized Red Onions

This is such a simple fish recipe, I’m not even sure it’s a “fish recipe,” per se. It’s just caramelized red onion on fish. Like…that’s it?

The thing is, it’s really good. Surprisingly good. Serve to your friends who maybe don’t even like fish good.

Something about plain white fish baked in a touch of lemon and butter then topped with sweet, jammy caramelized onions is just luxury. I don’t know. Maybe it’s just me.

But wait. Can you even caramelize red onions?

In short: yes. They’re a bit tougher than white onions and put up a bit more of a fight, but it’s the same basic principle: medium low heat for…ever. I add a bit of salt, maple syrup, and a tiny splash of apple cider vinegar to break down the onions and move things along, but even so, you’ll be waiting about 40 minutes.

The good news is that the fish bakes during this caramelizing time, so the whole dish is on the table in less than an hour. Get your onions ready; you’re in for a treat.

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White Fish with Caramelized Red Onions Recipe

Buttery fish and sweet onion perfection.

Makes: 4 servings

White Fish with Caramelized Red Onions

Prep time:

Cook time:

  • 4 fillets of white fish (4-5 ounces each), patted dry
  • 3 tablespoons butter, melted
  • 2 tablespoons lemon juice
  • 1 lemon, thinly sliced
  • 2 medium red onions, thinly sliced
  • 1 tablespoon olive oil
  • 1 tablespoon maple syrup
  • 1 tablespoon apple cider vinegar
  • Salt to taste
  • Pepper to taste

  1. Preheat the oven to 375 degrees Fahrenheit.
  2. In a large skillet, begin sauteeing the onions with one tablespoon of butter, the olive oil, the maple syrup, the vinegar, and salt and pepper over medium heat. Allow them to cook for about 15-20 minutes before proceeding to put the fish in the oven as described in the following steps.
  3. Keeping an eye on the onions, coat the fish fillets in the remaining butter and lemon juice (simply place the fish directly in a baking dish and pour the butter and lemon over the fillets, turning the fish to coat evenly).
  4. Place lemon slices on top of the fish and bake the fillets for 15-20 minutes, or until white and flaky throughout.
  5. While the fish bakes, continue to stir the onions ocassionally. If and when the onions stick to the pan, add a small splash of water and continue stirring.
  6. When the fish is finished baking, remove the fish from the oven to rest.
  7. You are ready to plate the dish when the onions are soft, sweet, and jammy. They should not have any "fight" (crispness) left in them.
  8. Top the fish with the onions, arranging with the lemon slices as desired. Enjoy.

Notes and Nutrition Information

  • Praise be, you can prepare your caramelized onions ahead of time. They’ll keep in the refrigerator for three-four days. The fish is best when baked fresh or served the very next day (store in an airtight container in the refrigerator).

  • One fourth of this recipe as written contains approximately 261 calories, 14 grams of fat, 9 grams of carbohydrates, 27 grams of protein, 1 gram of fiber, 6 grams of sugar, and 155 milligrams of sodium.

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