BBQ Barramundi Burger Grilled Cos

The first time I grilled lettuce on a BBQ, my neighbor leaned over the fence looking completely bewildered. Minutes later, after one bite of that smoky, charred cos cradling flaky barramundi and a kick of jalapeño tartare, he asked for the recipe instead of calling the authorities. Something magical happens when you hit fresh ingredients with flame and heat.

Last summer, we served these at a beach house weekend and my brother-in-law, who orders chicken parmigiana at every pub, went back for seconds. The brioche gets toasty and golden, the fish stays incredibly moist, and that sauce ties the whole vibrant mess together perfectly.

Ingredients

• Barramundi fillets: A beautiful Australian fish that holds up beautifully on the grill but any firm white fish like snapper or cod works perfectly
• Olive oil: Use a decent quality one here since youre relying on simple flavors to shine through
• Lemon: Grilling the lemon halves concentrates their natural sweetness and adds a subtle charred flavor to the tartare
• Jalapeños: Grilling mellows their heat slightly while adding a gorgeous smoky backbone to the sauce
• Good-quality mayonnaise: This is the base of your tartare so do not reach for the cheapest jar on the shelf
• Capers: These little briny buds add pops of brightness that cut through the rich fish and creamy sauce
• Fresh dill and parsley: The combination brings fresh herbal notes that lighten the whole burger
• Cos lettuce: Grilling this variety creates a sturdy, smoky wrap that does not wilt away instantly like softer greens
• Brioche buns: Their slight sweetness and sturdy texture are perfect for holding together all those juicy components

Instructions

Fire up the grill:

Get your BBQ or grill pan heated to medium-high so you have nice consistent heat for everything

Marinate the fish:

Whisk together olive oil, lemon zest, garlic, salt, and pepper then coat your barramundi fillets and let them sit for about 10 minutes

Prep your lettuce:

Separate the cos leaves and give them a light brush with olive oil so they are ready for the grill

Grill the aromatics:

Place lemon halves cut side down and jalapeño halves on the grill for 3 to 4 minutes until they are nicely charred and softened then finely chop the jalapeños and squeeze out that grilled lemon juice

Make the magic sauce:

Mix your mayonnaise with those grilled jalapeños, about 2 tablespoons of the grilled lemon juice, capers, both herbs, shallot, Dijon mustard, and season it all well then pop it in the fridge to chill

Cook the barramundi:

Grill those marinated fillets for 3 to 4 minutes per side until they are just cooked through and have beautiful light char marks

Get smoky with the lettuce:

Throw the cos leaves on the grill for just 1 to 2 minutes per side until they are slightly wilted and picked up that gorgeous grilled flavor

Toast your buns:

Give the buns a quick toast on the grill so they are warm and slightly crisp which helps hold everything together

Build your masterpiece:

Spread that tartare on both buns then layer with grilled cos lettuce, your beautiful barramundi, and fresh tomato and cucumber slices before crowning with the top bun

Serve immediately:

These are best enjoyed straight off the grill while everything is still warm and that sauce is nicely melted into all the nooks

Pin it

My friend Sarah who does not eat fish tried these at a summer potluck and confessed she was picking around the barramundi until she realized the smoky, zesty flavors were what made the whole burger sing. Sometimes the best discoveries happen when you stop overthinking and just let the grill do its work.

Choosing the Right Fish

Look for fillets that are about the same thickness so they cook evenly and hold up on the grill. Thinner pieces will cook too quickly and fall apart while thicker cuts might stay raw in the middle by the time the outside is charred.

Grill Temperature Mastery

Medium-high is your sweet spot because it gives you those gorgeous char marks without burning everything to a crisp. If your grill is running too hot, move the fish to a cooler zone and let it finish cooking through more gently.

Assembly Like a Pro

The bottom bun gets a thicker layer of tartare since it needs to soak up all those delicious juices from the fish. Place the grilled lettuce on the bottom to create a barrier that keeps your bun from getting soggy.

• Have all your components ready before you start grilling because everything comes together fast
• Use a light hand when pressing down on the burgers so you do not squeeze out all those precious juices
• Let the fish rest for just a minute after grilling to help it retain moisture inside

Pin it

There is something deeply satisfying about eating with your hands and getting a little messy in the best way possible. These burgers are summer on a plate, no forks required.

Recipe FAQ

→ Can I use frozen barramundi fillets?

Yes, thaw frozen fillets completely in the refrigerator before marinating. Pat them dry with paper towels to ensure the marinade adheres properly and the fish develops a nice char on the grill.

→ What's the best way to grill the cos lettuce?

Brush the leaves lightly with olive oil and grill for just 1-2 minutes per side. You want them slightly wilted with nice char marks but still retaining some crunch—don't overcook or they'll become limp.

→ Can I make the tartare sauce ahead of time?

Absolutely! The grilled lemon jalapeño tartare actually benefits from resting in the fridge for 1-2 hours, allowing the flavours to meld. It will keep for up to 3 days in an airtight container.

→ What other fish work well in this burger?

Firm white fish like snapper, cod, mahi-mahi, or even kingfish make excellent substitutes. Look for fillets that hold their shape well on the grill and won't flake apart when you flip them.

→ How can I reduce the heat level?

Remove all seeds and membranes from the jalapeños before grilling, or substitute with milder peppers like poblano. You can also reduce the jalapeño quantity to just one half in the tartare.

→ Can I cook this indoors without a BBQ?

A grill pan or heavy skillet works beautifully for both the fish and vegetables. Preheat the pan over medium-high heat and you'll achieve similar charred flavours and grill marks.