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Close-up of caramelized onion halves in a dark, glossy sauce, seasoned with pepper and salt, arranged closely together on a plate.

Miso Butter Onions

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These oven-roasted miso butter onions are the ultimate sweet-and-savory side dish. With just a handful of ingredients and minimal prep, they roast into jammy, golden perfection — finished with lemon zest and flaky salt.
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Prep Time 5 minutes
Cook Time 45 minutes
Total Time 50 minutes
Servings: 6
Course: Side Dish, Vegetables
Cuisine: side
Calories: 803
Ingredients Equipment Method Nutrition Notes

Ingredients
  

  • ½ cup shiro white miso
  • 8 tablespoon unsalted butter melted
  • ½ cup warm water
  • 4-8 small sweet onions halved
  • 1 lemon zested
  • Flaky salt to taste

Equipment

  • Cast iron skillet or oven-safe sauté pan
  • Microplane
  • Aluminum foil
  • Whisk

Method
 

  1. Preheat oven to 500°F.
  2. In a bowl, whisk together miso, melted butter, and warm water until smooth.
  3. Place onions cut-side down in a medium cast iron skillet. Pour the miso butter mixture over top.
  4. Cover tightly with foil and roast for 25 minutes.
  5. Remove foil, flip the onions, and check if pan needs a splash more water.
  6. Roast uncovered for 20 minutes more, or until deeply golden and caramelized.
  7. Transfer onions to a serving dish. Garnish with lemon zest and flaky salt. Serve warm.

Nutrition

Calories: 803kcalCarbohydrates: 0.1gProtein: 1gFat: 91gSaturated Fat: 58gPolyunsaturated Fat: 3gMonounsaturated Fat: 24gTrans Fat: 4gCholesterol: 241mgSodium: 12mgPotassium: 27mgSugar: 0.1gVitamin A: 2799IUCalcium: 27mgIron: 0.02mg

Notes

Storage: These keep in an airtight container in the fridge for up to 4 days. Reheat in a hot oven or skillet so the caramelized edges come back to life; the microwave will just steam them soft. They hold up surprisingly well as leftovers.

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