BBQ Barramundi Burger Grilled Cos

The smoky char of grilled lettuce still catches me off guard in the best way possible. My first attempt was completely accidental—I'd thrown everything on the grill at a beach BBQ and grabbed what I thought was regular lettuce for my fish burger. One bite in and I was standing there in my boardshorts, shocked at how the heat transformed humble cos into something sweet and smoky.

Last summer, my neighbor leaned over the fence while I was grilling the lettuce and asked if I'd finally lost it. Two burgers later, she was at my door demanding the tartare recipe. Now whenever I fire up the grill, I make extra because somehow word spreads down the street.

Ingredients

• Barramundi fillets: This Australian fish is perfect for grilling—firm enough to hold together, incredibly forgiving on heat timing, and stays juicy even with a good char
• Cos lettuce: Grilling romaine transforms it into something sweet and smoky, creating the perfect crunchy contrast to tender fish
• Jalapeños: Grilling tames their heat while adding depth—half the time I leave the seeds in because some days call for extra fire
• Lemon: Grilling the halves concentrates the citrus juice and adds a caramelized sweetness that makes regular lemon juice taste flat by comparison
• Capers and herbs: The fresh dill and parsley cut through the rich mayonnaise while capers provide those little bursts of briny brightness

Instructions

Fire up the grill:

Get your BBQ to medium-high—that sweet spot where you can hold your hand above the grates for about 3 seconds before pulling away

Marinate the fish:

Whisk together olive oil, lemon zest, garlic, salt, and pepper, then let the barramundi swim in it for 10 minutes while you prep everything else

Start the char:

Throw lemon halves cut-side down alongside jalapeños on the grill, letting them go 3–4 minutes until they're deeply colored and fragrant

Build the tartare:

Chop those grilled jalapeños finely, squeeze in about 2 tablespoons of charred lemon juice, then fold everything into the mayonnaise with capers, herbs, shallot, and mustard

Grill the star:

Cook the barramundi 3–4 minutes per side until it flakes gently but still holds its shape—dont be afraid of a little char

Grill the lettuce:

Brush cos leaves with olive oil and give them 1–2 minutes per side until slightly wilted with gorgeous grill marks

Toast the buns:

A quick 30 seconds cut-side down creates that sturdy foundation that keeps everything together

Assemble and serve:

Slather both bun halves with tartare, layer grilled lettuce first, then the fish, finish with tomato and cucumber, and get these into hands immediately

Save

My dad, who's suspicious of anything fancier than a meat patty, took one skeptical bite and went completely silent. He finished it without saying a word, then asked if there was enough fish for seconds. That's when I knew this wasn't just a recipe—it was a conversation changer.

Perfecting Your Grill Game

I've learned that rushing the preheat is where most people stumble. Let your grill get properly hot, and invest in good tongs—those flimsy ones will fail you exactly when you're trying to flip a delicate piece of fish.

The Fish Question

Barramundi is worth seeking out, but snapper or cod will absolutely work here. Just remember thinner fillets cook faster—check them a minute early and trust your eyes more than the timer.

Make It Yours

Some nights I skip the bun entirely and serve everything over rice with extra tartare. My sister wraps hers in large butter lettuce leaves for a lighter version. The grilled fish and that sauce work however you want to serve them.

• The tartare keeps for 3 days in the fridge and makes everything else taste better
• Grill extra vegetables while the heat is on—zucchini and eggplant love this treatment
• If it's raining, a cast-iron grill pan over high heat works beautifully

Save

There's something about grilling fish that makes an ordinary Tuesday dinner feel like an occasion. Pull up a plate, pour something cold, and pretend you're somewhere by the water.

Recipe FAQs

→ What makes barramundi ideal for burgers?

Barramundi's firm, meaty texture holds up beautifully on the grill without falling apart. Its mild, buttery flavour pairs perfectly with bold ingredients like grilled jalapeños while remaining delicate enough to let the tartare sauce shine through.

→ Can I prepare the tartare sauce ahead?

Absolutely. The grilled lemon jalapeño tartare develops even better flavour after chilling for a few hours. Make it up to 24 hours in advance and store it in an airtight container in the refrigerator. Bring it to room temperature 15 minutes before serving for optimal spreadability.

→ What other fish work as substitutes?

Firm white fish like snapper, cod, mahi-mahi, or halibut all work beautifully here. Look for fillets with similar thickness to ensure even cooking times. Avoid delicate fish like tilapia or sole, as they may break apart during grilling.

→ Why grill the lettuce leaves?

Grilling cos lettuce transforms its crisp texture into something slightly wilted and wonderfully smoky. The char adds depth that complements the fresh fish and zesty sauce, plus the warm lettuce contrasts beautifully with cool tomato and cucumber.

→ How do I know when the fish is done?

Barramundi is ready when it flakes easily with a fork and the flesh turns opaque throughout. Visual cues include light charring on the exterior and a firm but yielding texture when pressed gently. Aim for an internal temperature of 63°C (145°F).

→ What sides complement these burgers?

Crisp roasted potato wedges with sea salt, a fresh Greek salad, or charred corn on the cob all balance the richness beautifully. For a lighter option, serve with a simple arugula salad dressed in lemon vinaigrette to echo the citrus notes in the tartare.