Low Carb Grilled Fish with Red Onion and Scallions - 8 Day Jumpstart Approved

Low carb grilled snapper with red onion escabeche & grilled scallions.

This low carb grilled fish recipe is a succulent and fragrant dish, sure to shake things up on your low carb or keto diet. With deliciously spiced and easy home-pickled red onion and a hint of scallions, you’re sure to bring this one back again and again.

Low Carb Grilled Fish with Red Onion and Scallions Recipe

Serves 4
Per Serving—
Fat: 10g Protein: 42g Carbs: 3g


  • 1 large red onion, peeled, thinly sliced
  • 3/4 cup red wine vinegar
  • 1/2 teaspoon dried oregano
  • 1/2 teaspoon kosher salt
  • 1/4 teaspoon whole black peppercorns
  • 1/4 teaspoon ground cumin
  • 2 garlic cloves, whole, slightly crushed using the side of chef’s knife
  • 1 bay leaf
  • 4 (6-ounce) snapper fillets (or any firm white fish, such as mahi, rockfish, grouper, haddock)
  • 3 Tbsp. Olive oil
  • Salt and pepper
  • 1 bunch scallions


  1. Place sliced red onion in large, nonreactive bowl.
  2. In a small pot, heat vinegar, oregano, salt, peppercorns, cumin, garlic, and bay leaf. Bring to boil.
  3. Remove from heat and pour hot vinegar spice mixture over red onion.
  4. Let cool to room temperature. Cover and refrigerate at least 1 hour or overnight. Pickled onions will keep for up to 2 weeks refrigerated.
  5. Rub snapper with olive oil. Season with salt and pepper.
  6. Grill, skin side down, until lightly charred and almost cooked through, about 5 minutes (skin should release easily; if it sticks, grill an additional minute). Flip snapper and grill another 2 minutes.
  7. Lightly rub scallions with olive oil. Grill until lightly charred.
  8. Place snapper on a serving dish. Spoon onion escabeche on top.
  9. Serve with grilled scallions.

What Fish is Best for Keto and Low Carb?

Adding a variety of fish to your keto or low carb diet is a great idea. Many are packed with vitamins and minerals, not to mention healthy oils and Omega-3 fatty acids, which are essential to these types of diets.

Some of the best fish options for a keto diet include high-fat fish like salmon, herring, mackerel, and sardines. Other seafood choices that are lower in fat, such as trout, tilapia, halibut, rockfish, oysters, crab, and snapper, are a great way to introduce rich, olive oil or butter-based sauces with plenty of flavor and added fat while on a keto diet.

Salmon, trout, sardines, snapper, and mahi-mahi all make great low carb grilled fish and fit perfectly into a low carb meal plan.

How Many Carbs in a Red Onion?

While red onions are considered a high carb food by weight, they are eaten in such moderation that each serving will still work well within a low carb diet.

This low carb grilled fish recipe calls for one red onion (about 15 total carbs), divided into four servings. This means that each serving will contain approximately 3.5-4 carbs of red onion, leaving you worry-free and one meal closer to your low carb goals.

Red onions have an unmistakable sweetness which makes them a perfect candidate for pickling, which is just what you’ll do in this low carb grilled fish recipe. And if you’re a pickling beginner, don’t worry—it’s simple!

What’s the Difference Between Green Onions and Scallions?

You might be surprised to learn that the difference between green onions and scallions is simply their age. Green onions and scallions are actually harvested from the same plant, just at different stages of its maturity. Scallions are the younger form of the root plant, harvested when the white bulb near the roots is about the same width as the stem. Green onions, having been left to mature further, will have a more ovular-shaped bulb at their base.

The scallions in this low carb grilled fish dish provide it with a mild but distinctly onion flavor, with a slight grassy sweetness added to the mix. They also pack a bit of fiber to aid with digestion and feelings of fullness!

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