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Onion boil in foil opened on a plate with buttery Cajun-seasoned juices and fork-tender layers.
Linda

Onion Boil Recipe (Viral TikTok Foil-Baked Onion)

This viral onion boil recipe transforms one sweet onion into a buttery, fork-tender side with bold Cajun/Old Bay-style flavor. Despite the name, it’s typically foil-baked (not boiled), so the onion steams in its own seasoned butter for an easy, high-impact dish.
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Prep Time 10 minutes
Cook Time 1 hour
Total Time 1 hour 10 minutes
Servings: 2 servings
Course: Dinner, Lunch, Side Dish
Cuisine: American
Calories: 220
Ingredients Equipment Method Notes

Ingredients
  

Onion Boil Ingredients
  • 1 large sweet onion (Vidalia or sweet yellow) peeled; trim a thin slice off the root end so it sits flat
  • 2 tablespoons unsalted butter cubed (or use 1–2 tbsp olive oil)
  • 1/2 teaspoon Cajun seasoning adjust to taste
  • 1/2 teaspoon Old Bay seasoning optional, but gives classic “boil” flavor
  • 1/4 teaspoon kosher salt plus more to taste
  • 1/4 teaspoon garlic powder optional but recommended
  • 1/8 teaspoon black pepper or to taste
  • 1 clove garlic minced, optional
  • 1 pinch brown sugar optional, balances spice and boosts caramel notes
  • 1 tablespoon fresh parsley chopped, optional for serving

Equipment

  • Oven
  • Aluminum foil
  • Small baking dish or sheet pan
  • Chef's knife
  • Measuring Spoons

Method
 

    1. Preheat: Heat oven to 375°F (190°C).
    2. Prep the onion: Peel the onion. Trim a thin slice off the root end so it sits flat. Cut a small well into the top center (do not cut through the bottom).
    3. Season: Place butter into the well. Sprinkle Cajun seasoning, Old Bay (if using), salt, garlic powder, and pepper over the top so spices fall into the layers. Add minced garlic and/or a pinch of brown sugar if desired.
    4. Wrap: Set the onion in the center of a large sheet of foil and wrap tightly into a sealed packet. Place on a small baking dish or sheet pan.
    5. Bake: Bake 45–65 minutes, depending on onion size, until a fork slides in easily and layers separate with little resistance. If still firm, reseal and bake 10 more minutes.
    6. Serve: Open the foil carefully (hot steam). Spoon the buttery juices over the onion and eat layer by layer. Finish with parsley if desired.

Notes

Cook time tip: Onion size changes everything. Medium onions often finish closer to 45–55 minutes; large onions are typically 55–65 minutes.
Air fryer option: Wrap tightly in foil and air fry at 350°F for 45–60 minutes, checking doneness with a fork.
Flavor swaps: Try lemon pepper, smoky paprika, or a milder seasoning blend for a kid-friendly version.
Storage: Refrigerate leftovers in an airtight container and reheat gently (foil in a 350°F oven works best) to keep it juicy.