Onion Boil Recipe

This Onion Boil recipe transforms sweet onions into buttery, tender, seafood boil-inspired perfection with Cajun seasoning, garlic, and herbs. This easy foil packet side dish is perfect with steak, chicken, burgers, seafood, and backyard BBQ dinners.

Prep Time15

Cook Time1 15

Total Time1 30

Servings:

Calories: 207kcal

Author: Karin and Ken

Ingredients

6 large (8 oz) sweet onions
12 tablespoons butter
1 tablespoon paprika or smoked paprika for smoky favor
1 tablespoon garlic powder
2 teaspoons salt
3 teaspoons Cajun or seafood seasoning such as Old Bay
1 teaspoon dried thyme
1 teaspoon ground black pepper
Fresh parsley chopped, for serving

Instructions

Preheat the oven to 375 degrees Fahrenheit.
Peel the onions and trim a small amount from the root end so they sit flat, then use a spoon or melon baller to hollow out the center of each onion slightly.
Place each onion on a large sheet of heavy-duty foil. The foil traps moisture and butter, steaming the onions while roasting so they don't dry out.
Add 2 tablespoons of butter into the center of each onion.
In a small bowl, stir together the paprika, garlic powder, salt, Cajun seasoning, thyme, and black pepper.
Sprinkle the seasoning mixture evenly over and inside each onion.
Wrap each onion tightly in foil and place them on a large baking sheet.
Bake for 1 hour.
Carefully check one onion for doneness by opening foil with oven mitts on to avoid being burned by steam. Insert a knife into the center. If it slides in easily with little resistance, and onion is very soft and tender, they’re ready.
If not ready close foil and place back in oven for another 15 minutes and then check same onion again.
Once done, again carefully open all of the onions, spoon the buttery sauce over each onion and serve with fresh parsley, if desired.

Notes

This step is optional: Bake for 10 more minutes with foil open for darkened, lightly caramelized edges, if desired.
Start with the right setup: Use large sweet onions, leave enough root intact to hold them together, and wrap them tightly in heavy-duty foil to trap the buttery steam and prevent leaks while baking.
Build flavor from the inside out: Season inside the onion cavity, tuck the butter into the center, and let the flavors melt through every layer as they roast.
Cook until truly tender: Test with a knife for an extremely soft, tender, melt-in-your-mouth texture rather than just lightly softened onions.
Finish and serve for maximum flavor: Add cheese at the end if using, serve hot, and spoon every drop of the seasoned butter sauce over the onions before serving-it’s liquid gold.
Leftover Sauce: I serve the leftover buttery sauce spooned over rice, potatoes and vegetables. I also serve with a loaf of crusty bread to soak all of the sauce left on our plates.

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