Low Carb Keto Onion Boil

This low carb keto onion boil delivers all the cozy, buttery flavor of a classic seafood boil without the carb-heavy potatoes and corn. Sweet onions are gently caramelized in butter to create a rich, aromatic base, while cauliflower florets soak up a seasoned broth full of garlic, Old Bay, smoked paprika, and lemon. Juicy shrimp add satisfying protein, and optional smoked sausage, zucchini, or bell peppers make it easy to customize while staying keto-friendly. Ready in under an hour, this one-pot recipe works for quick weeknight dinners, meal prep, or a crowd-pleasing dinner party centerpiece that feels indulgent yet stays strictly keto.

Course Dinner, Main Course

Cuisine American

Keyword Cauliflower, keto, low-carb, one pot, onions, seafood boil, Shrimp

Prep Time 15

Cook Time 25

Total Time 40

Servings servings

Calories 345kcal

Equipment

large heavy-bottomed pot
Cutting board
Chef's knife
Wooden Spoon
measuring spoons
measuring cups
Colander

Ingredients

For the keto onion boil base

4 tablespoons unsalted butter divided
1 1/2 pounds yellow onions thinly sliced
3 cloves garlic minced
3 cups low sodium chicken broth or seafood stock
1 cup water
2 tablespoons Old Bay seasoning or similar seafood seasoning, to taste
1 teaspoon smoked paprika
1/4 teaspoon crushed red pepper flakes optional, for heat
1 1/4 teaspoons fine sea salt or to taste
1/2 teaspoon freshly ground black pepper
1 bay leaf

For the vegetables and protein

1 medium head cauliflower cut into medium florets, about 5 cups
1 1/4 pounds large shrimp peeled and deveined, tails on or off
6 ounces smoked sausage keto-friendly, sliced into 1/2 inch rounds, optional
1 small zucchini sliced into half moons, optional
1/2 medium red bell pepper seeded and sliced, optional

For finishing

2 tablespoons unsalted butter for finishing
1 lemon cut into wedges, plus 2 tablespoons juice
2 tablespoons fresh parsley chopped, optional for garnish

Instructions

Melt half of the butter in a large heavy-bottomed pot over medium heat until foamy.
Add the sliced onions and a pinch of salt, then cook, stirring occasionally, until very soft and lightly golden, about 12 to 15 minutes, reducing the heat if they begin to brown too quickly.
Stir in the minced garlic and cook until fragrant, about 1 minute, then add the remaining butter and let it melt into the onions.
Pour in the chicken broth and water, then add the Old Bay seasoning, smoked paprika, red pepper flakes if using, remaining salt, black pepper, and bay leaf, stirring to combine.
Bring the mixture to a gentle boil over medium high heat, then reduce to a steady simmer so the flavors meld.
Add the cauliflower florets to the pot, cover partially, and simmer until just tender when pierced with a fork, about 8 to 10 minutes.
If using smoked sausage, zucchini, or bell pepper, stir them into the pot once the cauliflower is nearly tender and cook for 3 to 4 minutes to soften slightly.
Add the shrimp to the simmering broth, stirring so they are submerged, and cook just until pink and opaque, about 3 to 4 minutes depending on size.
Turn off the heat, remove the bay leaf, and stir in the finishing butter and lemon juice until the butter is melted and the broth tastes bright and rich.
Taste the broth and adjust seasoning with additional salt, pepper, Old Bay, or lemon juice as desired.
Ladle the onions, cauliflower, shrimp, and broth into warm bowls, garnish with parsley and lemon wedges, and serve hot.

Notes

To keep this dish strictly keto, choose a smoked sausage with no added sugar and minimal fillers, or omit the sausage and rely on the shrimp alone. If you prefer a thicker, richer broth, reduce the liquid for a few extra minutes before adding the shrimp, or whisk in an extra tablespoon of butter off the heat for a silkier finish. Leftovers store well in an airtight container in the refrigerator for up to 4 days and reheat gently on the stovetop over low heat with a splash of extra broth. For meal prep, you can cook the onion base and vegetables ahead of time, then reheat and add raw shrimp just before serving so they stay tender and juicy. Serve this keto onion boil with a simple green salad or keto-friendly rolls to round out the meal without increasing carbs.

Nutrition