BBQ Barramundi Burger with Grilled Cos

The first time I grilled fish for burgers, I stood over the barbecue convinced I'd ruined dinner. The barramundi stuck to the grates, the lettuce refused to cooperate, and I wondered why I hadn't just made beef patties like everyone else. But one bite of that smoky, charred fillet with tangy tartare changed my entire perspective on what a burger could be. Now it's the summer dinner I request most often.

My neighbor leaned over the fence last summer while I was grilling the lettuce heads, looking completely confused. She thought I'd lost my mind until I handed her a fully assembled burger ten minutes later. Now she texts me whenever she sees cos lettuce on sale, asking if I'm making those fish burgers again.

Ingredients

• Barramundi fillets: This Australian fish has a natural sweetness and firm texture that won't fall apart on the grill, though snapper or cod work beautifully too
• Whole lemon: Grilling the lemon halves caramelizes the natural sugars and mellows the acidity, creating this smoky citrus brightness you can't get from fresh lemon juice
• Jalapeños: The grill tames their harsh heat while bringing out this sweet, earthy flavor that makes the tartare sauce completely addictive
• Cos lettuce: The thick ribs stand up to grilling without wilting into nothing, and they develop this incredible charred flavor that makes the burger feel substantial
• Good mayonnaise: Since this sauce carries the dish, use something you genuinely like eating straight from the jar

Instructions

Fire up the grill:

Get your barbecue to medium-high, letting the grates get nice and hot so everything gets those gorgeous char marks immediately.

Marinate the fish:

Whisk together olive oil, lemon zest, garlic, salt, and pepper, then let the barramundi swim in it while you prep everything else.

Start the sauce components:

Place lemon halves cut-side down on the grill alongside those jalapeño halves, letting them get deeply charred and softened before removing them.

Grill the barramundi:

Cook the marinated fish for about four minutes per side until it's just opaque in the center and has beautiful char lines running across it.

Char the lettuce:

Brush those cos leaves with olive oil and grill them briefly just until they pick up some color and start to soften at the edges.

Toast the buns:

Give the split buns a quick dance on the grill so they're warm and slightly crisp, which keeps everything together better.

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These burgers have become our go-for when friends come over for summer dinners because everyone assembles theirs slightly differently. Some people double up on the tartare, others want extra grilled jalapeños on top, and I've seen my brother eat three without coming up for air. There's something about that combination of smoky fish, charred lettuce, and zesty sauce that makes people completely forget they're eating fish instead of beef.

Making It Your Own

I've discovered that leaving a few jalapeño seeds in the sauce creates this slow burn that some people absolutely love. You can also add smoked paprika to the fish marinade for even more depth, or swap the cos lettuce for baby gem if you want something more delicate. The beauty here is that the grilling technique does most of the work, so you can play with flavors without worrying about technique.

What To Serve Alongside

Crispy roasted potatoes seasoned with sea salt and rosemary work beautifully here because they echo the charred flavors from the grill. A simple green salad with vinaigrette helps cut through the rich tartare sauce, and during summer I love serving these with grilled corn on the cob. An Australian Sauvignon Blanc or a cold pale ale balances the heat and richness perfectly.

Getting Ahead

The tartare sauce actually gets better after a few hours in the fridge, so make it in the morning if you're planning a dinner party. You can also marinate the fish up to four hours ahead, though I wouldn't go longer or the citrus starts breaking down the texture. Everything else happens so quickly that you'll want to prep all your components before you fire up the grill.

• Toast your buns just before serving so they don't get soggy from the sauce
• Keep the grilled fish on a warm plate, not directly on the grill, while you finish the lettuce
• Have everything within arm's reach before you start because this comes together fast

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Every time I make these, I'm reminded that some of the best discoveries come from kitchen experiments that nearly go wrong. That first messy, imperfect grilled fish burger taught me more about summer cooking than dozens of carefully planned meals ever could.

Recipe Questions & Answers

→ Can I use a different fish instead of barramundi?

Yes, snapper, cod, or any firm white fish fillet works beautifully as a substitute for barramundi in this burger.

→ How do I make the tartare sauce less spicy?

Simply remove all seeds from the jalapeños before grilling, or reduce the amount to one jalapeño half for milder heat.

→ Can I cook this indoors without a BBQ?

A grill pan or cast-iron skillet works perfectly for cooking the barramundi, grilling the lettuce, and toasting the buns indoors.

→ How long should I marinate the fish?

Ten minutes is ideal for the barramundi to absorb the lemon-garlic flavors without breaking down the texture.

→ What sides pair well with this burger?

Crisp potato wedges, garden salad, or even grilled corn on the cob complement the fresh, zesty flavors of this Australian-style fish burger.

→ Can I make the tartare sauce ahead of time?

Absolutely, the grilled lemon jalapeño tartare can be prepared up to 24 hours in advance and stored refrigerated in an airtight container.